Modified supported chromium catalysts and ethylene-based polymers produced therefrom

ABSTRACT

Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/732,020, filed on Sep. 17, 2018, the disclosure ofwhich is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure generally relates to supported chromium catalystsand to ethylene polymers produced therefrom, and more particularly,relates to catalysts with a hydrocarbon group attached to the chromiumand to the unique polymer features that result from using such catalystsin ethylene-based polymerizations.

BACKGROUND OF THE INVENTION

Chromium catalysts are among the most common catalysts used in olefinpolymerizations. Supported chromium catalysts often are prepared byimpregnating chromium onto a solid support, e.g., a solid oxide,followed by a calcining step. Generally, calcining is conducted in anoxidizing atmosphere, such that the chromium species within thesupported chromium catalyst can be converted to hexavalent chromium.

The present invention is generally directed to reducing the supportedchromium catalyst to an average oxidation state less than +6, and usingthe reduced catalyst to polymerize olefins, such as ethylene alone orwith an alpha-olefin comonomer.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify required oressential features of the claimed subject matter. Nor is this summaryintended to be used to limit the scope of the claimed subject matter.

A supported chromium catalyst is provided in one aspect of thisinvention, and in this aspect, the supported chromium catalyst cancomprise a solid support, and from about 0.01 to about 20 wt. % chromium(based on the weight of the catalyst). The chromium has an averagevalence of less than or equal to about 5.25, and at least one bondingsite on the chromium has a ligand characterized by one of the followingformulas: —O-Hydrocarbon group or —O-Halogenated hydrocarbon group. Thesolid support can comprise a solid oxide (e.g., silica orsilica-titania), a chemically-treated solid oxide (e.g., sulfatedalumina or fluorided silica-coated alumina), or a zeolite (e.g., amedium pore zeolite or a large pore zeolite, often with a binder).

An ethylene polymer is provided in another aspect of this invention, andin this aspect, the ethylene polymer can be characterized by a Mw in arange from about 100,000 to about 400,000 g/mol, at least about 2 wt. %of the polymer having a molecular weight greater than 1,000,000 g/mol,and at least about 1.5 wt. % of the polymer having a molecular weightless than 1000 g/mol. Such ethylene polymers have relatively broadmolecular weight distributions, often with ratios of Mw/Mn ranging from30 to 80.

An ethylene homopolymer is provided in yet another aspect of thisinvention, and in this aspect, the ethylene homopolymer can have anumber of methyl short chain branches (SCB's) in a range from about 3.5to about 15 per 1000 total carbon atoms, a number of butyl SCB's of lessthan or equal to about 0.6 per 1000 total carbon atoms, and a ratio ofMw/Mn in a range from about 4 to about 10. The average molecular weightis not particularly limited, but typically Mw ranges from about 30,000to about 200,000 g/mol. Due to the relatively high branch content,despite the lack of comonomer, the density can be below 0.945 g/cm³,below 0.94 g/cm³, or below 0.935 g/cm³.

An ethylene polymer is provided in still another aspect of thisinvention, and in this aspect, the ethylene polymer can comprise aterminal branched alkane group, a terminal cyclic alkane group, aterminal aromatic group, or a terminal halogenated hydrocarbon group.Thus, the chain end can be a moiety not found in traditional ethylenehomopolymerization and ethylene/α-olefin copolymerization. For instance,the terminal group or chain end can be a cyclic alkane group or anaromatic group, such as benzene or toluene.

Both the foregoing summary and the following detailed descriptionprovide examples and are explanatory only. Accordingly, the foregoingsummary and the following detailed description should not be consideredto be restrictive. Further, features or variations may be provided inaddition to those set forth herein. For example, certain aspects may bedirected to various feature combinations and sub-combinations describedin the detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 presents an illustration of a chromium catalyst with a bondingsite for a hydrocarbon group, and representative polymer chainsincorporating the hydrocarbon group as a chain end.

FIG. 2 presents a plot of the range of wavelengths emitted from red,blue, and violet LED diodes used to irradiate the supported chromiumcatalyst of Example 27.

FIG. 3 present a plot of the IR reflectance of a Cr/silica catalyst ofExample 28 calcined at 650° C.

FIG. 4 presents a plot of the molecular weight distributions of thepolymers of Examples 88-89 and 93-94.

DEFINITIONS

To define more clearly the terms used herein, the following definitionsare provided. Unless otherwise indicated, the following definitions areapplicable to this disclosure. If a term is used in this disclosure butis not specifically defined herein, the definition from the IUPACCompendium of Chemical Terminology, 2^(nd) Ed (1997), can be applied, aslong as that definition does not conflict with any other disclosure ordefinition applied herein, or render indefinite or non-enabled any claimto which that definition is applied. To the extent that any definitionor usage provided by any document incorporated herein by referenceconflicts with the definition or usage provided herein, the definitionor usage provided herein controls.

Herein, features of the subject matter are described such that, withinparticular aspects, a combination of different features can beenvisioned. For each and every aspect and each and every featuredisclosed herein, all combinations that do not detrimentally affect thecatalysts, compositions, processes, or methods described herein arecontemplated with or without explicit description of the particularcombination. Additionally, unless explicitly recited otherwise, anyaspect or feature disclosed herein can be combined to describe inventivecatalysts, compositions, processes, or methods consistent with thepresent disclosure.

Generally, groups of elements are indicated using the numbering schemeindicated in the version of the periodic table of elements published inChemical and Engineering News, 63(5), 27, 1985. In some instances, agroup of elements can be indicated using a common name assigned to thegroup; for example, alkali metals for Group 1 elements, alkaline earthmetals for Group 2 elements, transition metals for Group 3-12 elements,and halogens or halides for Group 17 elements.

The term “hydrocarbon” whenever used in this specification and claimsrefers to a group or compound containing only carbon and hydrogen,whether saturated or unsaturated. Other identifiers can be utilized toindicate the presence of particular groups in the hydrocarbon (e.g.,halogenated hydrocarbon indicates the presence of one or more halogenatoms replacing an equivalent number of hydrogen atoms in thehydrocarbon). Non-limiting examples of hydrocarbons include alkanes(linear, branched, and cyclic), alkenes (olefins), and aromatics, amongothers.

For any particular compound or group disclosed herein, any name orstructure (general or specific) presented is intended to encompass allconformational isomers, regioisomers, stereoisomers, and mixturesthereof that can arise from a particular set of substituents, unlessotherwise specified. The name or structure (general or specific) alsoencompasses all enantiomers, diastereomers, and other optical isomers(if there are any) whether in enantiomeric or racemic forms, as well asmixtures of stereoisomers, as would be recognized by a skilled artisan,unless otherwise specified. For instance, a general reference to pentaneincludes n-pentane, 2-methyl-butane, and 2,2-dimethylpropane; and ageneral reference to a butyl group includes a n-butyl group, a sec-butylgroup, an iso-butyl group, and a t-butyl group.

Unless otherwise specified, the term “substituted” when used to describea group, for example, when referring to a substituted analog of aparticular group, is intended to describe any non-hydrogen moiety thatformally replaces a hydrogen in that group, and is intended to benon-limiting. Also, unless otherwise specified, a group or groups canalso be referred to herein as “unsubstituted” or by equivalent termssuch as “non-substituted,” which refers to the original group in which anon-hydrogen moiety does not replace a hydrogen within that group.Moreover, unless otherwise specified, “substituted” is intended to benon-limiting and include inorganic substituents or organic substituentsas understood by one of ordinary skill in the art.

The terms “contacting” and “combining” are used herein to describecatalysts, compositions, processes, and methods in which the materialsor components are contacted or combined together in any order, in anymanner, and for any length of time, unless otherwise specified. Forexample, the materials or components can be blended, mixed, slurried,dissolved, reacted, treated, impregnated, compounded, or otherwisecontacted or combined in some other manner or by any suitable method ortechnique.

In this disclosure, while catalysts, compositions, processes, andmethods are described in terms of “comprising” various components orsteps, the catalysts, compositions, processes, and methods also can“consist essentially of” or “consist of” the various components orsteps, unless stated otherwise.

The terms “a,” “an,” and “the” are intended to include pluralalternatives, e.g., at least one. For instance, the disclosure of “areductant,” “a solid oxide,” etc., is meant to encompass one, ormixtures or combinations of more than one, reductant, solid oxide, etc.,unless otherwise specified.

The term “polymer” is used herein generically to include olefinhomopolymers, copolymers, terpolymers, and the like, as well as alloysand blends thereof. The term “polymer” also includes impact, block,graft, random, and alternating copolymers. A copolymer can be derivedfrom an olefin monomer and one olefin comonomer, while a terpolymer canbe derived from an olefin monomer and two olefin comonomers.Accordingly, “polymer” encompasses copolymers and terpolymers.Similarly, the scope of the term “polymerization” includeshomopolymerization, copolymerization, and terpolymerization. Therefore,an ethylene polymer would include ethylene homopolymers, ethylenecopolymers (e.g., ethylene/α-olefin copolymers), ethylene terpolymers,and the like, as well as blends or mixtures thereof. Thus, an ethylenepolymer encompasses polymers often referred to in the art as LLDPE(linear low density polyethylene) and HDPE (high density polyethylene).As an example, an ethylene copolymer can be derived from ethylene and acomonomer, such as 1-butene, 1-hexene, or 1-octene. If the monomer andcomonomer were ethylene and 1-hexene, respectively, the resultingpolymer can be categorized an as ethylene/1-hexene copolymer. The term“polymer” also includes all possible geometrical configurations, ifpresent and unless stated otherwise, and such configurations can includeisotactic, syndiotactic, and random symmetries.

Herein, ethylene polymers also encompass ethylene-based polymers havingnon-traditional terminal groups or chain ends. Traditional terminalgroups or chain ends include those that typically result (e.g.,saturated methyl chain ends, vinyl chain ends) from the polymerizationof ethylene, either alone or with alpha-olefin comonomers, such as1-butene, 1-hexene, and 1-octene. Non-traditional terminal groups orchain ends encompassed herein can include various branched alkane,cyclic alkane, aromatic, and halogenated hydrocarbon groups.

Several types of ranges are disclosed in the present invention. When arange of any type is disclosed or claimed, the intent is to disclose orclaim individually each possible number that such a range couldreasonably encompass, including end points of the range as well as anysub-ranges and combinations of sub-ranges encompassed therein. Forexample, when a chemical compound having a certain number of carbonatoms is disclosed or claimed, the intent is to disclose or claimindividually every possible number that such a range could encompass,consistent with the disclosure herein. For example, the disclosure of aC₁ to C₁₈ halogenated hydrocarbon group, or in alternative language, ahalogenated hydrocarbon group having from 1 to 18 carbon atoms, as usedherein, refers to a group that can have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms, as well as any rangebetween these two numbers (for example, a C₁ to C₈ halogenatedhydrocarbon group), and also including any combination of ranges betweenthese two numbers (for example, a C₂ to C₄ and a C₁₂ to C₁₆ halogenatedhydrocarbon group).

Similarly, another representative example follows for the amount ofchromium contained in the supported catalyst. By a disclosure that theamount of chromium can be in a range from about 0.1 to about 15 wt. %,the intent is to recite that the amount of chromium can be any amount inthe range and, for example, can be equal to about 0.1, about 0.2, about0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9,about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8,about 9, about 10, about 11, about 12, about 13, about 14, or about 15wt. %. Additionally, the amount of chromium can be within any range fromabout 0.1 to about 15 wt. % (for example, from about 0.1 to about 5 wt.%), and this also includes any combination of ranges between about 0.1and about 15 wt. % (for example, the amount of chromium can be in arange from about 0.5 to about 2.5 wt. %, or from about 5 to about 15 wt.%). Further, in all instances, where “about” a particular value isdisclosed, then that value itself is disclosed. Thus, the disclosurethat the amount of chromium can be from about 0.1 to about 15 wt. % alsodiscloses an amount of chromium from 0.1 to 15 wt. % (for example, from0.1 to 5 wt. %), and this also includes any combination of rangesbetween 0.1 and 15 wt. % (for example, the amount of chromium can be ina range from 0.5 to 2.5 wt. %, or from 5 to 15 wt. %). Likewise, allother ranges disclosed herein should be interpreted in a manner similarto these examples.

The term “about” means that amounts, sizes, formulations, parameters,and other quantities and characteristics are not and need not be exact,but can be approximate including being larger or smaller, as desired,reflecting tolerances, conversion factors, rounding off, measurementerrors, and the like, and other factors known to those of skill in theart. In general, an amount, size, formulation, parameter or otherquantity or characteristic is “about” or “approximate” whether or notexpressly stated to be such. The term “about” also encompasses amountsthat differ due to different equilibrium conditions for a compositionresulting from a particular initial mixture. Whether or not modified bythe term “about,” the claims include equivalents to the quantities. Theterm “about” can mean within 10% of the reported numerical value, andoften within 5% of the reported numerical value.

Although any methods, devices, and materials similar or equivalent tothose described herein can be used in the practice or testing of theinvention, the typical methods, devices, and materials are hereindescribed.

All publications and patents mentioned herein are incorporated herein byreference for the purpose of describing and disclosing, for example, theconstructs and methodologies that are described in the publications,which might be used in connection with the presently describedinvention.

DETAILED DESCRIPTION OF THE INVENTION

A hexavalent chromium catalyst can be converted into the divalent formby reduction in CO at elevated temperatures, for instance, at 200-800°C. The reduced catalyst then can be treated with an adjuvant hydrocarbonor halogenated hydrocarbon compound, which can be an alkane (linear orbranched), a cycloalkane, or an aromatic. It is believed that theadjuvant compound forms a hydrocarbon-containing ligand on the modifiedcatalyst, and when used in an olefin polymerization, the polymerizationbegins with and incorporates the hydrocarbon moiety from the modifiedcatalyst as the first terminal group or chain end.

A hexavalent chromium catalyst can be reduced to an average valence ofless than +6 in the presence of a suitable light source and hydrocarbonreductant. It is believed that the reductant compound forms ahydrocarbon-containing ligand on the modified catalyst, and when used inan olefin polymerization, the polymerization begins with andincorporates the hydrocarbon moiety from the modified catalyst as thefirst terminal group or chain end. FIG. 1 shows an illustration of thechromium catalyst with a bonding site for the hydrocarbon group, andrepresentative polymer chains incorporating the hydrocarbon group as achain end.

Ethylene Polymers

Generally, the polymers disclosed herein are ethylene-based polymers, orethylene polymers, encompassing homopolymers of ethylene as well ascopolymers, terpolymers, etc., of ethylene and at least one olefincomonomer. Comonomers that can be copolymerized with ethylene often canhave from 3 to 20 carbon atoms in their molecular chain. For example,typical comonomers can include, but are not limited to, propylene,1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and the like, orcombinations thereof. In an aspect, the olefin comonomer can comprise aC₃-C₁₈ olefin; alternatively, the olefin comonomer can comprise a C₃-C₁₀olefin; alternatively, the olefin comonomer can comprise a C₄-C₁₀olefin; alternatively, the olefin comonomer can comprise a C₃-C₁₀α-olefin; alternatively, the olefin comonomer can comprise a C₄-C₁₀α-olefin; alternatively, the olefin comonomer can comprise 1-butene,1-hexene, 1-octene, or any combination thereof; or alternatively, thecomonomer can comprise 1-hexene. Typically, the amount of the comonomer,based on the total weight of monomer (ethylene) and comonomer, can be ina range from about 0.01 to about 20 wt. %, from about 0.1 to about 10wt. %, from about 0.5 to about 15 wt. %, from about 0.5 to about 8 wt.%, or from about 1 to about 15 wt. %.

In one aspect, the ethylene polymer of this invention can comprise anethylene/α-olefin copolymer, while in another aspect, the ethylenepolymer can comprise an ethylene homopolymer, and in yet another aspect,the ethylene polymer of this invention can comprise an ethylene/α-olefincopolymer and an ethylene homopolymer. For example, the ethylene polymercan comprise an ethylene/1-butene copolymer, an ethylene/1-hexenecopolymer, an ethylene/1-octene copolymer, an ethylene homopolymer, orany combination thereof; alternatively, an ethylene homopolymer;alternatively, an ethylene/1-butene copolymer, an ethylene/1-hexenecopolymer, an ethylene/1-octene copolymer, or any combination thereof;or alternatively, an ethylene/1-hexene copolymer.

An illustrative and non-limiting example of a first ethylene polymer(e.g., comprising an ethylene homopolymer and/or an ethylene copolymer)consistent with the present invention can have a Mw in a range fromabout 100,000 to about 400,000 g/mol, at least about 2 wt. % of thepolymer having a molecular weight greater than 1,000,000 g/mol, and atleast about 1.5 wt. % of the polymer having a molecular weight less than1000 g/mol. Another illustrative and non-limiting example of a secondethylene homopolymer consistent with the present invention can have anumber of methyl short chain branches (SCB's) in a range from about 3.5to about 15 per 1000 total carbon atoms, a number of butyl SCB's of lessthan or equal to about 0.6 per 1000 total carbon atoms, and a ratio ofMw/Mn in a range from about 4 to about 10. Yet another illustrative andnon-limiting example of a third ethylene polymer (e.g., comprising anethylene homopolymer and/or an ethylene copolymer) consistent with thepresent invention can comprise a terminal branched alkane group, aterminal cyclic alkane group, a terminal aromatic group, or a terminalhalogenated hydrocarbon group.

Referring now to the first ethylene polymer, which can be characterizedby a Mw in a range from about 100,000 to about 400,000 g/mol, at leastabout 2 wt. % of the polymer having a molecular weight greater than1,000,000 g/mol, and at least about 1.5 wt. % of the polymer having amolecular weight less than 1000 g/mol. This polymer, unexpectedly, has arelatively large fraction of the polymer with very low molecular weights(less than 1000 g/mol) in combination with a relatively large fractionof the polymer with very high molecular weights (greater than 1,000,000g/mol).

In an aspect, the Mw of the first ethylene polymer often can range fromabout 100,000 to about 300,000 g/mol, from about 150,000 to about400,000 g/mol, from about 200,000 to about 400,000 g/mol, or from about200,000 to about 300,000 g/mol. Additionally or alternatively, the firstethylene polymer can have a Mn from about 3,000 to about 10,000 g/mol inone aspect, from about 4,000 to about 9,000 g/mol in another aspect,from about 4,000 to about 8,000 g/mol in another aspect, from about4,000 to about 7,000 g/mol in yet another aspects, and from about 5,000to about 6,000 g/mol in still another aspect. Additionally oralternatively, the first ethylene polymer can have a Mz in a range fromabout 1,500,000 to about 4,000,000 g/mol, from about 2,000,000 to about3,500,000 g/mol, or from about 2,000,000 to about 3,000,000 g/mol.Additionally or alternatively, the first ethylene polymer can have a Mp(peak molecular weight) at a relatively low molecular weight, such asfrom about 10,000 to about 60,000 g/mol, from about 10,000 to about50,000 g/mol, from about 10,000 to about 40,000 g/mol, or from about15,000 to about 30,000 g/mol.

Consistent with the first polymer having a relatively large fraction ofthe polymer with very low molecular weights (less than 1000 g/mol) incombination with a relatively large fraction of the polymer with veryhigh molecular weights (greater than 1,000,000 g/mol), the firstethylene polymer has a very broad molecular weight distribution, asreflected by the ratio of Mw/Mn. While not limited thereto, the firstethylene polymer can have a ratio of Mw/Mn from about 30 to about 80,from about 35 to about 75, from about 35 to about 60, from about 40 toabout 55, or from about 45 to about 50. The ratio of Mz/Mw of the firstethylene polymer is not nearly as large, and typically falls in one ormore of the following ranges: from about 6 to about 13, from about 8 toabout 11, from about 8.5 to about 10.5, and/or from about 9 to about 10.

At least about 2 wt. % of the first ethylene polymer can have amolecular weight greater than 1,000,000 g/mol. Illustrative andnon-limiting ranges for the amount of the first ethylene polymer havinga molecular weight greater than 1,000,000 g/mol include from about 2 toabout 10 wt. %, from about 3 to about 10 wt. %, from about 4 to about 9wt. %, from about 5 to about 9 wt. %, or from about 5 to about 8 wt. %,and the like. Also indicative of the relatively large “high molecularweight fraction” of the first ethylene polymer is the highest molecularweight detected (using the analytical test described herein), which isat least about 5,000,000 g/mol, at least about 6,000,000 g/mol, at leastabout 7,000,000 g/mol, or at least about 8,000,000 g/mol.

At least about 1.5 wt. % of the first ethylene polymer can have amolecular weight less than 1000 g/mol. Illustrative and non-limitingranges for the amount of the first ethylene polymer having a molecularweight less than 1000 g/mol include from about 1.5 to about 8 wt. %,from about 2 to about 7 wt. %, from about 3 to about 6 wt. %, from about3.5 to about 5 wt. %, or from about 4 to about 4.5 wt. %, and the like.Also indicative of the relatively large “low molecular weight fraction”of the first ethylene polymer is the amount of the polymer having amolecular weight less than 3162 g/mol, which often ranges from about 8to about 20 wt. %, from about 10 to about 20 wt. %, from about 12 toabout 18 wt. %, from about 13 to about 17 wt. %, or from about 14 toabout 16 wt. % of the polymer.

Notwithstanding the relatively large fraction of the polymer with verylow molecular weights in combination with a relatively large fraction ofthe polymer with very high molecular weights, a majority of the polymeroften resides in the 10,000 to 1,000,000 g/mol range of molecularweight. While not limited thereto, from about 53 to about 73 wt. %, fromabout 55 to about 70 wt. %, from about 58 to about 68 wt. %, or fromabout 61 to about 65 wt. %, of the first ethylene polymer has amolecular weight in the 10,000 to 1,000,000 g/mol range.

Referring now to the second ethylene polymer, in this case an ethylenehomopolymer, which can be characterized by a number of methyl shortchain branches (SCB's) in a range from about 3.5 to about 15 per 1000total carbon atoms, a number of butyl SCB's of less than or equal toabout 0.6 per 1000 total carbon atoms, and a ratio of Mw/Mn in a rangefrom about 4 to about 10. This second ethylene homopolymer has asurprising combination of a relatively large amount of methyl branchesalong with a relatively small amount of butyl branches.

In some aspects, the number of methyl SCB's of the second ethylenehomopolymer can range from about 3.5 to about 12, from about 3.5 toabout 10.5, from about 4 to about 12, from about 4 to about 10, fromabout 4.5 to about 10, or from about 5 to about 10 methyl SCB's per 1000total carbon atoms. Additionally or alternatively, the number of butylSCB's of the homopolymer can be less than or equal to about 0.5, lessthan or equal to about 0.4, less than or equal to about 0.3, or lessthan or equal to about 0.2 butyl SCB's per 1000 total carbon atoms.

The molecular weight distribution of the second ethylene homopolymer, asreflected by the ratio of Mw/Mn, typically ranges from about 4 to about10, but in some aspects, can range from about 4 to about 9, from about 4to about 8.5, or from about 4 to about 8, while in other aspects, theratio of Mw/Mn of the homopolymer ranges from about 4.5 to about 10,from about 4.5 to about 8.5, or from about 5 to about 9. The ratio ofMz/Mw of the ethylene homopolymer is not particularly limited, but oftencan range from about 2.5 to about 7; alternatively, from about 2.5 toabout 6; alternatively, from about 3 to about 7; or alternatively, fromabout 3 to about 6.

The second ethylene homopolymer can encompass a broad range of molecularweights, such as having a Mw in a range from about 30,000 to about200,000 g/mol in one aspect, from about 30,000 to about 140,000 g/mol inanother aspect, from about 35,000 to about 150,000 g/mol in yet anotheraspect, and from about 40,000 to about 135,000 g/mol in still anotheraspect.

Unexpectedly, the homopolymer disclosed herein also can be characterizedby a ratio of vinyl chain ends to saturated chain ends (vinyl/saturated)per 1000 total carbon atoms that is less than or equal to about 1. Infurther aspects, the vinyl/saturated ratio can be less than or equal toabout 0.5; alternatively, less than or equal to about 0.3; oralternatively, less than or equal to about 0.1. While not being limitedthereto, the homopolymer can further have a number of ethyl SCB's fromabout 0.8 to about 5, from about 1 to about 5, from about 0.8 to about4, from about 1 to about 4, from about 0.8 to about 3.5, from about 1 toabout 3.5, or from about 1.5 to about 3.5 ethyl SCB's per 1000 totalcarbon atoms.

The significant branching of the second ethylene homopolymer suppressesthe density, and therefore, densities in the range of from about 0.93 toabout 0.96 g/cm³ are achievable. Representative ranges for thehomopolymer density include from about 0.93 to about 0.955 g/cm³, fromabout 0.935 to about 0.955 g/cm³, from about 0.935 to about 0.950 g/cm³,from about 0.938 to about 0.948 g/cm³, and the like.

Referring now to the third ethylene polymer, which can comprise aterminal branched alkane group, a terminal cyclic alkane group, aterminal aromatic group, or a terminal halogenated hydrocarbon group.Thus, instead of traditional methyl and vinyl chain ends, the thirdethylene polymer—unexpectedly—can contain a chain end that is a branchedalkane group, a cyclic alkane group, an aromatic group, or a halogenatedhydrocarbon group. The chemical “groups” described herein—such as alkanegroups and aromatic groups—are general terms to encompass a variety ofgroups in which any number (“one or more”) hydrogen atoms are removed,as necessary for the situation and to conform with the rules of chemicalvalence. For instance, an illustrative cyclic alkane group is acyclohexane group, which encompasses moieties in which any number ofhydrogen atoms are removed from a cyclohexane, such as a cyclohexylgroup.

The bulk polymer is not particularly limited, and in one aspect, thethird ethylene polymer can comprise an ethylene homopolymer, while inanother aspect, the third ethylene polymer can comprise anethylene/α-olefin copolymer, and in yet another aspect, the thirdethylene polymer can comprise an ethylene/1-butene copolymer, anethylene/1-hexene copolymer, and/or an ethylene/1-octene copolymer, andin still another aspect, the third ethylene polymer can comprise anethylene/1-hexene copolymer.

The branched alkane group which can be the terminal group or the chainend is not particularly limited, and can be any suitable carbon numberbranched alkane group, such as a C₄ to C₃₆ branched alkane group, a C₄to C₁₈ branched alkane group, a C₁₀ to C₃₆ branched alkane group, or aC₁₀ to C₃₆ branched alkane group. Illustrative branched alkane groupsinclude neopentane, iso-pentane, iso-octane, and the like.

Likewise, the cyclic alkane group is not particularly limited, and anycarbon number cyclic alkane group can be the terminal group or chain endof the third ethylene polymer. For instance, C₄ to C₃₆ cyclic alkanegroups, C₄ to C₁₈ cyclic alkane groups, C₆ to C₁₈ cyclic alkane groups,and C₆ to C₁₀ cyclic alkane groups are contemplated herein, and specificnon-limiting examples include cyclobutane, cyclopentane, cyclohexane,cyclooctane, and the like.

Similarly, the aromatic group which can be the terminal group or thechain end is not particularly limited, and any suitable carbon numberaromatic group is encompassed herein. Representative non-limitingexamples include a benzene group, a toluene group, an ethylbenzenegroup, a xylene group, a mesitylene group, and the like.

Additionally, the halogenated hydrocarbon group is not particularlylimited, and any carbon number halogenated hydrocarbon group can be theterminal group or chain end of the third ethylene polymer. For instance,C₁ to C₃₆ halogenated hydrocarbon groups, C₁ to C₁₈ halogenatedhydrocarbon groups, C₁ to C₁₂ halogenated hydrocarbon groups, or C₁ toC₈ halogenated hydrocarbon groups can present at the terminal end of thethird ethylene polymer, and a non-limiting example of such halogenatedhydrocarbon groups is tetrafluoroethane.

If not already specified, the first ethylene polymer, the secondethylene polymer, and the third ethylene polymer consistent with thepresent invention also can have any of the polymer properties listedbelow and in any combination.

Ethylene polymers (e.g., ethylene homopolymers and/or copolymers)produced in accordance with some aspects of this invention generally canhave a melt index (MI) from 0 to about 100 g/10 min. Melt indices in therange from 0 to about 50 g/10 min, from 0 to about 25 g/10 min, or from0 to about 10 g/10 min, are contemplated in other aspects of thisinvention. For example, a polymer of the present invention can have amelt index in a range from 0 to about 5, from 0 to about 3, from 0 toabout 1, or from 0 to about 0.5 g/10 min.

Ethylene polymers produced in accordance with some aspects of thisinvention can have a high load melt index (HLMI) of less than or equalto about 200, less than or equal to about 150, or less than or equal toabout 100 g/10 min. Suitable ranges for the HLMI can include, but arenot limited to, from 0 to about 150, from about 2 to about 120, fromabout 1 to about 100, from about 1 to about 80, from about 2 to about80, from about 4 to about 60, from about 8 to about 60, from about 1 toabout 50, from about 4 to about 50, from about 3 to about 40, or fromabout 6 to about 40 g/10 min.

The densities of ethylene polymers produced using the chromium catalystsand the processes disclosed herein often are greater than or equal toabout 0.89 g/cm³. In one aspect of this invention, the density of theolefin polymer can be in a range from about 0.89 to about 0.96 g/cm³.Yet, in another aspect, the density can be in a range from about 0.91 toabout 0.95 g/cm³, such as, for example, from about 0.91 to about 0.94g/cm³, from about 0.92 to about 0.955 g/cm³, or from about 0.93 to about0.955 g/cm³.

In an aspect, ethylene polymers described herein can have aweight-average molecular weight (Mw) in a range from about 50,000 toabout 2,000,000, from about 50,000 to about 1,000,000, from about 50,000to about 700,000, from about 75,000 to about 500,000, from about 100,000to about 500,000, from about 100,000 to about 400,000, or from about150,000 to about 300,000 g/mol. Additionally or alternatively, ethylenepolymers described herein can have a number-average molecular weight(Mn) in a range from about 2,000 to about 250,000, from about 2,000 toabout 100,000, from about 2,000 to about 50,000, from about 5,000 toabout 200,000, from about 5,000 to about 150,000, or from about 5,000 toabout 50,000 g/mol. In another aspect, ethylene polymers describedherein can have a Mn in a range from about 10,000 to about 100,000, fromabout 10,000 to about 75,000, from about 25,000 to about 150,000, orfrom about 50,000 to about 150,000 g/mol.

Ethylene copolymers, for example, produced using the polymerizationprocesses and catalysts described herein can, in some aspects, have adecreasing comonomer distribution, generally, the higher molecularweight components of the polymer have less comonomer incorporation thanthe lower molecular weight components. In one aspect, the number ofshort chain branches (SCB's) per 1000 total carbon atoms of the polymercan be less at Mw than at Mn. In another aspect, the number of SCB's per1000 total carbon atoms of the polymer can be less at Mz than at Mw. Inyet another aspect, the number of SCB's per 1000 total carbon atoms ofthe polymer can be less at Mz than at Mn.

The first ethylene polymer, the second ethylene polymer, and the thirdethylene polymer can be produced with chromium-based catalysts.Therefore, these ethylene polymers can contain no measurable amount ofnickel or iron (catalyst residue), i.e., less than 0.1 ppm by weight. Insome aspects, the ethylene polymer can contain, independently, less than0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm, of nickel and iron.Moreover, metallocene and Ziegler-Natta catalyst systems are notrequired. Therefore, the ethylene polymers can contain no measurableamount of titanium, zirconium, and hafnium (catalyst residue), i.e.,less than 0.1 ppm by weight. In some aspects, the ethylene polymer cancontain, independently, less than 0.08 ppm, less than 0.05 ppm, or lessthan 0.03 ppm, of titanium, zirconium, and hafnium.

Articles of manufacture can be formed from, and/or can comprise, thefirst, second, and third ethylene polymers of this invention and,accordingly, are encompassed herein. For example, articles which cancomprise the polymers of this invention can include, but are not limitedto, an agricultural film, an automobile part, a bottle, a container forchemicals, a drum, a fiber or fabric, a food packaging film orcontainer, a food service article, a fuel tank, a geomembrane, ahousehold container, a liner, a molded product, a medical device ormaterial, an outdoor storage product, outdoor play equipment, a pipe, asheet or tape, a toy, or a traffic barrier, and the like. Variousprocesses can be employed to form these articles. Non-limiting examplesof these processes include injection molding, blow molding, rotationalmolding, film extrusion, sheet extrusion, profile extrusion,thermoforming, and the like. Additionally, additives and modifiers oftenare added to these polymers in order to provide beneficial polymerprocessing or end-use product attributes. Such processes and materialsare described in Modern Plastics Encyclopedia, Mid-November 1995 Issue,Vol. 72, No. 12; and Film Extrusion Manual—Process, Materials,Properties, TAPPI Press, 1992; the disclosures of which are incorporatedherein by reference in their entirety. In some aspects of thisinvention, an article of manufacture can comprise any of the ethylenepolymers described herein, and the article of manufacture can be or cancomprise a pipe, a molded product (e.g., blow molded), or a film (e.g.,a blown film). Typical additives that can be present in the ethylenepolymer and/or the article of manufacture include antioxidants, acidscavengers, antiblock additives, slip additives, colorants, fillers,processing aids, UV inhibitors, and the like, as well as combinationsthereof.

Chromium Catalysts

Aspects of this invention are directed to supported chromium catalysts,and such catalysts can comprise a solid support, and from about 0.01 toabout 20 wt. % chromium, based on the weight of the catalyst. Thechromium can have an average valence of less than or equal to about5.25, and at least one bonding site on the chromium can have a ligandcharacterized by one of the following formulas: —O-Hydrocarbon group or—O-Halogenated hydrocarbon group.

Various solid supports can be used for the supported chromium catalyst,such as conventional solid oxides and zeolites. Generally, the solidoxide can comprise oxygen and one or more elements selected from Group2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 of the periodic table,or comprise oxygen and one or more elements selected from the lanthanideor actinide elements (See: Hawley's Condensed Chemical Dictionary,11^(th) Ed., John Wiley & Sons, 1995; Cotton, F. A., Wilkinson, G.,Murillo, C. A., and Bochmann, M., Advanced Inorganic Chemistry, 6^(th)Ed., Wiley-Interscience, 1999). For example, the solid oxide cancomprise oxygen and an element, or elements, selected from Al, B, Be,Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Mn, Mo, Ni, Sb, Si, Sn, Sr, Th, Ti, V,W, P, Y, Zn, and Zr. Illustrative examples of solid oxide materials orcompounds that can be used as solid support can include, but are notlimited to, Al₂O₃, B₂O₃, BeO, Bi₂O₃, CdO, Co₃O₄, Cr₂O₃, CuO, Fe₂O₃,Ga₂O₃, La₂O₃, Mn₂O₃, MoO₃, NiO, P₂O₅, Sb₂O₅, SiO₂, SnO₂, SrO, ThO₂,TiO₂, V₂O₅, WO₃, Y₂O₃, ZnO, ZrO₂, and the like, including mixed oxidesthereof, and combinations thereof.

The solid oxide can encompass oxide materials such as silica, “mixedoxide” compounds thereof such as silica-titania, and combinations ormixtures of more than one solid oxide material. Mixed oxides such assilica-titania can be single or multiple chemical phases with more thanone metal combined with oxygen to form the solid oxide. Examples ofmixed oxides that can be used as solid oxide include, but are notlimited to, silica-alumina, silica-coated alumina, silica-titania,silica-zirconia, alumina-titania, alumina-zirconia, zinc-aluminate,alumina-boria, silica-boria, aluminum phosphate, aluminophosphate,aluminophosphate-silica, titania-zirconia, and the like, or acombination thereof. In some aspects, the solid support can comprisesilica, silica-alumina, silica-coated alumina, silica-titania,silica-titania-magnesia, silica-zirconia, silica-magnesia, silica-boria,aluminophosphate-silica, and the like, or any combination thereof.Silica-coated aluminas are encompassed herein; such oxide materials aredescribed in, for example, U.S. Pat. Nos. 7,884,163 and 9,023,959,incorporated herein by reference in their entirety.

The percentage of each oxide in a mixed oxide can vary depending uponthe respective oxide materials. As an example, a silica-alumina (orsilica-coated alumina) typically has an alumina content from 5 wt. % to95 wt. %. According to one aspect, the alumina content of thesilica-alumina (or silica-coated alumina) can be from 5 wt. % alumina 50wt. % alumina, or from 8 wt. % to 30 wt. % alumina. In another aspect,high alumina content silica-aluminas (or silica-coated aluminas) can beemployed, in which the alumina content of these materials typicallyranges from 60 wt. % alumina to 90 wt. % alumina, or from 65 wt. %alumina to 80 wt. % alumina.

In one aspect, the solid oxide can comprise silica-alumina,silica-coated alumina, silica-titania, silica-zirconia, alumina-titania,alumina-zirconia, zinc-aluminate, alumina-boria, silica-boria, aluminumphosphate, aluminophosphate, aluminophosphate-silica, titania-zirconia,or a combination thereof; alternatively, silica-alumina; alternatively,silica-coated alumina; alternatively, silica-titania; alternatively,silica-zirconia; alternatively, alumina-titania; alternatively,alumina-zirconia; alternatively, zinc-aluminate; alternatively,alumina-boria; alternatively, silica-boria; alternatively, aluminumphosphate; alternatively, aluminophosphate; alternatively,aluminophosphate-silica; or alternatively, titania-zirconia.

In another aspect, the solid oxide can comprise silica, alumina,titania, thoria, stania, zirconia, magnesia, boria, zinc oxide, a mixedoxide thereof, or any mixture thereof. In yet another aspect, the solidsupport can comprise silica, alumina, titania, or a combination thereof;alternatively, silica; alternatively, alumina; alternatively, titania;alternatively, zirconia; alternatively, magnesia; alternatively, boria;or alternatively, zinc oxide. In still another aspect, the solid oxidecan comprise silica, alumina, silica-alumina, silica-coated alumina,aluminum phosphate, aluminophosphate, heteropolytungstate, titania,zirconia, magnesia, boria, zinc oxide, silica-titania, silica-yttria,silica-zirconia, alumina-titania, alumina-zirconia, zinc-aluminate,alumina-boria, silica-boria, aluminophosphate-silica, titania-zirconia,and the like, or any combination thereof.

Consistent with certain aspects of this invention, the catalyst cancomprise a chemically-treated solid oxide as the support, and where thechemically-treated solid oxide comprises a solid oxide (any solid oxidedisclosed herein) treated with an electron-withdrawing anion (anyelectron withdrawing anion disclosed herein). The electron-withdrawingcomponent used to treat the solid oxide can be any component thatincreases the Lewis or Brønsted acidity of the solid oxide upontreatment (as compared to the solid oxide that is not treated with atleast one electron-withdrawing anion). According to one aspect, theelectron-withdrawing component can be an electron-withdrawing anionderived from a salt, an acid, or other compound, such as a volatileorganic compound, that serves as a source or precursor for that anion.Examples of electron-withdrawing anions can include, but are not limitedto, sulfate, bisulfate, fluoride, chloride, bromide, iodide,fluorosulfate, fluoroborate, phosphate, fluorophosphate,trifluoroacetate, triflate, fluorozirconate, fluorotitanate,phospho-tungstate, tungstate, molybdate, and the like, includingmixtures and combinations thereof. In addition, other ionic or non-ioniccompounds that serve as sources for these electron-withdrawing anionsalso can be employed.

It is contemplated that the electron-withdrawing anion can be, or cancomprise, fluoride, chloride, bromide, phosphate, triflate, bisulfate,or sulfate, and the like, or any combination thereof, in some aspectsprovided herein. In other aspects, the electron-withdrawing anion cancomprise sulfate, bisulfate, fluoride, chloride, bromide, iodide,fluorosulfate, fluoroborate, phosphate, fluorophosphate,trifluoroacetate, triflate, fluorozirconate, fluorotitanate, and thelike, or combinations thereof. Yet, in other aspects, theelectron-withdrawing anion can comprise fluoride and/or sulfate.

The chemically-treated solid oxide generally can contain from about 1wt. % to about 30 wt. % of the electron-withdrawing anion, based on theweight of the chemically-treated solid oxide. In particular aspectsprovided herein, the chemically-treated solid oxide can contain fromabout 1 to about 20 wt. %, from about 2 wt. % to about 20 wt. %, fromabout 3 wt. % to about 20 wt. %, from about 2 wt. % to about 15 wt. %,from about 3 wt. % to about 15 wt. %, from about 3 wt. % to about 12 wt.%, or from about 4 wt. % to about 10 wt. %, of the electron-withdrawinganion, based on the total weight of the chemically-treated solid oxide.

In an aspect, the chemically-treated solid oxide can comprise fluoridedalumina, chlorided alumina, bromided alumina, sulfated alumina,fluorided silica-alumina, chlorided silica-alumina, bromidedsilica-alumina, sulfated silica-alumina, fluorided silica-zirconia,chlorided silica-zirconia, bromided silica-zirconia, sulfatedsilica-zirconia, fluorided silica-titania, fluorided silica-coatedalumina, fluorided-chlorided silica-coated alumina, sulfatedsilica-coated alumina, phosphated silica-coated alumina, and the like,as well as any mixture or combination thereof.

In another aspect, the chemically-treated solid oxide employed in thecatalysts and processes described herein can be, or can comprise, afluorided solid oxide and/or a sulfated solid oxide, non-limitingexamples of which can include fluorided alumina, sulfated alumina,fluorided silica-alumina, sulfated silica-alumina, fluoridedsilica-zirconia, fluorided silica-coated alumina, sulfated silica-coatedalumina, and the like, as well as combinations thereof. Additionalinformation on chemically-treated solid oxide can be found in, forinstance, U.S. Pat. Nos. 7,294,599, 7,601,665, 7,884,163, 8,309,485,8,623,973, and 8,703,886, which are incorporated herein by reference intheir entirety.

Representative examples of supported chromium catalysts (in which asolid oxide is the support) include, but are not limited to,chromium/silica, chromium/silica-titania,chromium/silica-titania-magnesia, chromium/silica-alumina,chromium/silica-coated alumina, chromium/aluminophosphate,chromium/alumina, chromium/alumina borate, and the like, or anycombination thereof. In one aspect, for instance, the supported chromiumcatalyst can comprise chromium/silica, while in another aspect, thesupported chromium catalyst can comprise chromium/silica-titania, and inyet another aspect, the supported chromium catalyst can comprisechromium/silica-alumina and/or chromium/silica-coated alumina. Incircumstances in which the supported chromium catalyst compriseschromium/silica-titania, any suitable amount of titanium can be present,including from about 0.1 to about 20 wt. %, from about 0.5 to about 15wt. %, from about 1 to about 10 wt. %, or from about 1 to about 6 wt. %titanium, based on the total weight of the catalyst.

Representative examples of supported chromium catalysts (in which achemically-treated solid oxide is the support) include, but are notlimited to, chromium/sulfated alumina, chromium/fluorided alumina,chromium/fluorided silica-alumina, chromium/fluorided silica-coatedalumina, and the like, as well as combinations thereof.

Consistent with certain aspects of this invention, the supportedchromium catalyst can comprise a zeolite as the support, i.e., achromium supported zeolite. Any suitable zeolite can be used, forinstance, large pore and medium pore zeolites. Large pore zeolites oftenhave average pore diameters in a range of from about 7 Å to about 12 Å,and non-limiting examples of large pore zeolites include L-zeolite,Y-zeolite, mordenite, omega zeolite, beta zeolite, and the like. Mediumpore zeolites often have average pore diameters in a range of from about5 Å to about 7 Å. Combinations of zeolitic supports can be used.

Additional representative examples of zeolites that can be used in thesupported catalyst include, for instance, a ZSM-5 zeolite, a ZSM-11zeolite, a EU-1 zeolite, a ZSM-23 zeolite, a ZSM-57 zeolite, an ALPO4-11zeolite, an ALPO4-41 zeolite, a Ferrierite framework type zeolite, andthe like, or any combination thereof.

In the catalyst, the zeolite can be bound with a support matrix (orbinder), non-limiting examples of which can include silica, alumina,magnesia, boria, titania, zirconia, various clays, and the like,including mixed oxides thereof, as well as mixtures thereof. Forexample, the catalyst support can comprise a binder comprising alumina,silica, a mixed oxide thereof, or a mixture thereof. The zeolite can bebound with the binder using any method known in the art. While not beinglimited thereto, the catalyst can comprise a zeolite and from about 3wt. % to about 35 wt. % binder; alternatively, from about 5 wt. % toabout 30 wt. % binder; or alternatively, from about 10 wt. % to about 30wt. % binder. These weight percentages are based on the total weight ofthe catalyst.

The amount of chromium in the supported chromium catalyst also is notparticularly limited. However, the amount of chromium in the supportedchromium catalyst typically ranges from about 0.01 to about 20 wt. %;alternatively, from about 0.01 to about 10 wt. %; alternatively, fromabout 0.05 to about 15 wt. %; alternatively, from about 0.1 to about 15wt. %; alternatively, from about 0.2 to about 10 wt. %; alternatively,from about 0.1 to about 5 wt. %; or alternatively, from about 0.5 toabout 2.5 wt. %. These weight percentages are based on the amount ofchromium relative to the total weight of the catalyst.

Likewise, the amount of chromium in an oxidation state of +5 or less incatalyst is not particularly limited, and can fall within the sameranges. Thus, the chromium catalyst can contain from about 0.01 to about20 wt. %, from about 0.01 to about 10 wt. %, from about 0.05 to about 15wt. %, from about 0.1 to about 15 wt. %, from about 0.2 to about 10 wt.%, from about 0.1 to about 5 wt. %, or from about 0.5 to about 2.5 wt. %of chromium in an oxidation state of +5 or less, based on the totalweight of the catalyst. Traditional chromium (VI) catalysts often willhave an orange, yellow, or tan color, while catalysts with chromium inreduced oxidation states often will have a green, blue, gray, or blackcolor.

Generally, in the supported chromium catalyst, less than or equal toabout 75 wt. % of the chromium can be in the hexavalent state in oneaspect, while less than or equal to about 50 wt. % of the chromium canbe in the hexavalent state in another aspect, and less than or equal toabout 40 wt. % of the chromium can be in the hexavalent state in yetanother aspect, and less than or equal to about 30 wt. % of the chromiumcan be in the hexavalent state in still another aspect. These values arebased on the total amount of chromium in the catalyst.

Additionally or alternatively, the chromium in the supported chromiumcatalyst can be characterized by an average valence of less than orequal to about 5.25. More often, the catalyst contains chromium havingan average valence of less than or equal to about 5; alternatively, anaverage valence of less than or equal to about 4.75; alternatively, anaverage valence of less than or equal to about 4.5; alternatively, anaverage valence of less than or equal to about 4.25; or alternatively,an average valence of less than or equal to about 4.

Additionally or alternatively, the molar ratio of the hydrocarbon group(i.e., hydrocarbon or halogenated hydrocarbon) to chromium in thesupported catalyst often ranges from about 0.25:1 to about 2:1, whilenot being limited thereto. For instance, in some aspects, the molarratio of the hydrocarbon group to chromium can fall in a range fromabout 0.5:1 to about 2:1, from about 0.5:1 to about 1.5:1, from about0.75:1 to about 1.75:1, or from about 0.75:1 to about 1.25:1, and thelike.

The total pore volume of the supported chromium catalyst also is notparticularly limited. For instance, the supported chromium catalyst canhave a total pore volume in a range from about 0.1 to about 5 mL/g, fromabout 0.15 to about 5 mL/g, from about 0.1 to about 3 mL/g, from about0.5 to about 2.5 mL/g, or from about 0.15 to about 2 mL/g. Likewise, thesurface area of the supported chromium catalyst is not limited to anyparticular range. Generally, however, the supported chromium catalystcan have a BET surface area in a range from about 50 to about 2000 m²/g,from about 50 to about 700 m²/g, from about 50 to about 400 m²/g, fromabout 100 to about 1200 m²/g, from about 150 to about 525 m²/g, or fromabout 200 to about 400 m²/g. BET surface areas are determined using theBET nitrogen adsorption method of Brunaur et al., J. Am. Chem. Soc., 60,309 (1938). Total pore volumes are determined in accordance with Halsey,G. D., J. Chem. Phys. (1948), 16, pp. 931.

The supported chromium catalyst can have any suitable shape or form, andsuch can depend on the type of process that is employed to use thecatalyst (e.g., loop slurry and fluidized bed for polymerization, andother processes for non-polymerization processes, such as fixed bed).Illustrative and non-limiting shapes and forms include powder, round orspherical (e.g., a sphere), ellipsoidal, pellet, bead, cylinder, granule(e.g., regular and/or irregular), trilobe, quadralobe, ring, wagonwheel, monolith, and the like, as well as any combination thereof.Accordingly, various methods can be utilized to prepare the catalystparticles, including, for example, extrusion, spray drying, pelletizing,marumerizing, spherodizing, agglomeration, oil drop, and the like, aswell as combinations thereof.

In some aspects, the supported chromium catalyst can have a relativelysmall particle size, in which representative ranges for the average(d50) particle size of the supported chromium catalyst can include fromabout 10 to about 500 microns, from about 25 to about 250 microns, fromabout 20 to about 100 microns, from about 40 to about 160 microns, orfrom about 40 to about 120 microns. The d50 particle size, or median oraverage particle size, refers to the particle size for which 50% of thesample has a smaller size and 50% of the sample has a larger size, andis determined using laser diffraction in accordance with ISO 13320.

In other aspects, the supported chromium catalyst can be in the form ofpellets or beads—and the like—having an average size ranging from about1/16 inch to about ½ inch, or from about ⅛ inch to about ¼ inch. Asnoted above, the size of the catalyst particles can be varied to suitthe particular process that is utilizing the chromium catalyst.

A variety of hydrocarbons and halogenated hydrocarbons can be part of aligand bound to the chromium in a —O-Hydrocarbon group or —O-Halogenatedhydrocarbon group, inclusive of saturated aliphatic hydrocarbon groups,unsaturated aliphatic hydrocarbon groups, linear aliphatic hydrocarbongroups, branched aliphatic hydrocarbon groups, and cyclic aliphatichydrocarbon groups. Thus, the hydrocarbon group can be a linear alkanegroup, a branched alkane group, or a cyclic alkane group, as well ashalogenated versions thereof. Alternatively, the hydrocarbon group canbe an aromatic group, such as a benzene group, a toluene group, and thelike, as well as substituted versions and/or halogenated versionsthereof. Hence, in one aspect, an alkoxy group can be bonded to thechromium, while in another aspect, an aryloxy group can be bonded to thechromium.

Any suitable carbon number hydrocarbon group can be used, such that thehydrocarbon group can be a C_(n) hydrocarbon group. While not beinglimited thereto, the integer n can range from 1 to 36 in one aspect,from 1 to 18 in another aspect, from 1 to 12 in yet another aspect, andfrom 1 to 8 in still another aspect. Therefore, the hydrocarbon group(or halogenated hydrocarbon group) can be any suitable carbon numberalkane group, for instance, a C₁ to C₃₆ alkane group; alternatively, aC₁ to C₁₈ alkane group; alternatively, a C₁ to C₁₂ alkane group; oralternatively, a C₁ to C₈ alkane group, and analogous halogenated alkanegroups.

Likewise, the hydrocarbon group (or halogenated hydrocarbon group) canbe any suitable carbon number aromatic group, for instance, a C₆ to C₃₆aromatic group; alternatively, a C₆ to C₁₈ aromatic group;alternatively, a C₆ to C₁₂ aromatic group; or alternatively, a C₆ to C₈aromatic group, and analogous halogenated aromatic groups.

Illustrative examples of alkane and aromatic hydrocarbon groups caninclude a methane group, an ethane group, a propane group, a butane(e.g., n-butane or isobutane) group, a pentane (e.g., n-pentane,neopentane, or isopentane) group, a hexane group, a heptane group, anoctane group, a nonane group, a decane group, an undecane group, adodecane group, a tridecane group, a tetradecane group, a pentadecanegroup, a hexadecane group, a heptadecane group, an octadecane group, abenzene group, a toluene group, an ethylbenzene group, a xylene group, amesitylene group, and the like, as well as halogenated versions thereof.

EXAMPLES

The invention is further illustrated by the following examples, whichare not to be construed in any way as imposing limitations to the scopeof this invention. Various other aspects, modifications, and equivalentsthereof, which after reading the description herein, can suggestthemselves to one of ordinary skill in the art without departing fromthe spirit of the present invention or the scope of the appended claims.

Melt index (MI, g/10 min) was determined in accordance with ASTM D1238at 190° C. with a 2.16 kg weight, I₁₀ (g/10 min) was determined inaccordance with ASTM D1238 at 190° C. with a 10 kg weight, and high loadmelt index (HLMI, g/10 min) was determined in accordance with ASTM D1238at 190° C. with a 21.6 kg weight. BET surface areas can be determinedusing the BET nitrogen adsorption method of Brunaur et al., J. Am. Chem.Soc., 60, 309 (1938). Total pore volumes can be determined in accordancewith Halsey, G. D., J. Chem. Phys. (1948), 16, pp. 931. The d50 particlesize, or median or average particle size, refers to the particle sizefor which 50% of the sample has a smaller size and 50% of the sample hasa larger size, and can be determined using laser diffraction inaccordance with ISO 13320.

In these examples, supported chromium catalysts comprising hexavalentchromium species were irradiated under UV-visible light in the presenceof various reductants and under various treatment conditions. Prior toirradiation, the supported chromium catalysts were calcined at thespecified temperature in dry air (an oxidizing atmosphere) in afluidized bed for three hours, in order to convert the chromium speciesto their respective hexavalent oxidation state.

Unless otherwise specified, for each of the examples provided below,about two grams of the supported catalyst were first charged to anair-tight glass container at 25° C., optionally in the presence of areductant. The glass container was then exposed to light as noted inTables I-IV below. For examples where the glass container was exposed tosunlight, the container was taken outside and placed in direct sunlight,slowly rotating the container to ensure even exposure of the supportedchromium catalyst mixture. For examples where the glass container wasexposed to artificial light, the sample was placed in a box containing afluorescent light emitting light in the UV-Vis spectrum. Examples notexposed to light were stored under dim lighting, or wrapped in foil toensure no light entered the glass container. Reduction of the supportedchromium catalysts was monitored by the presence of a color change. Foreach catalyst, the starting hexavalent supported chromium catalyst hadan orange color which darkened significantly upon exposing the catalystto light in the presence of a reductant, indicating reduction of thesupported chromium catalyst starting material.

The reduced chromium catalysts, prepared as described above, were usedin polymerization experiments conducted in a 2-L stainless-steelautoclave reactor containing 1.2 L of isobutane as a diluent. Thepolymerization reactions were conducted in the dark, and ethylene wasfed on demand to maintain a reactor pressure of 550 psig. The reactorwas maintained at the 105° C. (unless otherwise specified) throughoutthe experiment by an automated heating-cooling system. Forcopolymerization experiments, 1-hexene was flushed in with the initialethylene charge. At the end of each experiment, the resulting polymerwas dried at 60° C. under reduced pressure.

Examples 1-20

Examples 1-20 employed a supported chromium catalyst comprisingsilica-titania (2.5 wt. % Ti and 1.0 wt. % Cr). The Cr/silica-titaniacatalyst had a BET surface area of 500 m²/g, a pore volume of 2.5 mL/g,and an average particle size of 130 μm. The Cr/silica-titania catalystswere calcined at 850° C. (except as indicated otherwise) in dry air (anoxidizing atmosphere) in order to convert the respective chromiumspecies to the hexavalent oxidation state. Tables I-II summarize thevarious catalyst reductions, catalyst productivity (grams ofpolyethylene per gram of catalyst), catalyst activity (grams ofpolyethylene per gram of catalyst per hour), and resultant polymer HLMI,I₁₀, and MI (g/10 min).

Comparative Examples 1-6 describe attempts to reduce the hexavalentchromium present on the Cr/silica-titania catalysts without exposing thecatalyst to light in the presence of a reductant. As shown in Examples1-2, when no reductant was present, the catalyst was unaffected by light(orange). In contrast, Examples 9-20 each underwent a color changefollowing exposure to light after as little as 10 minutes in thepresence of various reductants, the color change persisting after beingremoved from the light. Unexpectedly, when a reductant was present, evenshort exposures of light resulted in a color change, indicatingreduction of the chromium to a lower valence chromium species. In fact,the catalyst activity and melt index potential of the catalysts wereimproved by relatively short exposures to light, as shown by InventiveExamples 9, 13, and 17.

In addition to reductions with ethylene, the reduction step wassurprisingly effective for hydrocarbons that are relatively difficult tooxidize, such as methane and benzene. Examples 3-6 demonstrate thedifficulty of reducing Cr(VI) catalysts in the presence of thehydrocarbon methane using conventional methods. In Examples 3-6, methanewas passed through the catalysts in a fluidized bed (without light), andrequired heating to 350° C. and above (Examples 4-6) before a colorchange was observed. In contrast, and unexpectedly, exposing samples ofthe catalyst to sunlight in the presence of methane, without heating,induced a color change in the catalyst mixture within minutes (Example13). Even more surprising, reduction in the presence of methane by theinventive method was not accompanied by a significant loss in catalystactivity and melt index potential, indicating that the catalyst producedin the presence of light is fundamentally distinct from that produced byconventional methods. Note the higher catalyst activities and melt indexproperties of Examples 13-14 as compared to Examples 3-6.

Examples 15-17 provide additional examples of reductions using compoundsthat are traditionally poor reductants, including tetrafluoroethane andbenzene. Each example demonstrated a distinct and quick color changeupon exposure to light. The use of benzene resulted in increasedcatalyst activity and comparable melt index properties to ComparativeExamples 1-2.

Inventive Examples 18-19 were conducted using H₂ as the reductant.Surprisingly, the reduction produced an active catalyst within minuteshaving increased MI potential and comparable activity, relative to theComparative Example 7. This result is unexpected, particularly becausethermal reduction in hydrogen typically results in a relatively inactivecatalyst with low MI potential.

Comparative Example 8 is provided as direct comparison for Example 20,where the Cr/silica-titania catalyst was calcined at slightly elevatedtemperatures (871° C.), prior to being reduced in the presence ofmethane for 6 hr. The resulting reduced Cr/silica-titania catalysts wereused in an ethylene/1-hexene copolymerization reaction, andsurprisingly, both the catalyst activity and melt index properties ofthe catalyst reduced in the presence of light were higher than theCr(VI)/silica-titania catalyst of Comparative Example 8.

TABLE I Comparative Examples 1-8 using Cr/silica-titania without lightreduction Productivity Activity HLMI I₁₀ MI Example Reductant TreatmentColor (gPE/gCat) (g/g/h) (g/10 min) (g/10 min) (g/10 min) 1 None None, 1orange 2315 3307 110 27.2 1.97 week 2 None light, orange 2434 3319 9623.7 1.75 1 week 3 methane none orange 3087 3705 39 8.7 0.55 (300° C.) 4methane none green 2209 3488 28 6.5 0.46 (350° C.) 5 methane none green1823 3646 22 5.2 0.32 (400° C.) 6 methane none green 2338 2646 17 3.80.23 (450° C.) 7* none none orange 2919 3434 47 10.3 0.64 8*^(†) nonenone orange 3095 12379 62 14.2 0.91 *The catalyst was calcined at atemperature of 871° C. ^(†)The polymerization reaction was conducted at100° C. in the presence of 5 mL 1-hexene.

TABLE II Inventive Examples 9-20 using Cr/silica-titania with lightreduction Productivity Activity HLMI I₁₀ MI Example Reductant TreatmentColor (gPE/gCat) (g/g/h) (g/10 min) (g/10 min) (g/10 min)  9 10 psigsunlight, blue/gray 2980 5430 88 23.1 1.72 ethylene 10 min 10 12 psigsunlight, blue/gray 2231 2434 71 17.6 1.38 ethylene 4 h 11 12 psigsunlight, blue/gray 2443 3858 57 14.6 1.10 ethylene 4 h 12 10 psigsunlight blue/gray 2212 2328 30 7.1 0.50 ethylene 6 h, 3 h (×2) 13 10psig sunlight, green 2915 6780 114 26.3 1.95 methane 10 min 14 10 psigsunlight, green 3099 5469 70 16.7 1.17 methane 6 h 15 10 psig sunlight,green 1554 1636 29 7.1 0.54 Freon 2 h 16 10 psig sunlight, green 28201945 29 7.0 0.55 Freon 2 h 17 4 drops sunlight red/violet 3951 5268 8920.8 1.46 benzene 15 min 18* 10 psig sunlight, green 3297 2953 52 11.90.88 H₂ 15 min 19* 10 psig sunlight gray/green 3437 3124 31 7.3 0.50 H₂2 h 20*^(†) 10 psig sunlight green 3239 14951 67 14.7 0.92 methane 6 h*The catalyst was calcined at a temperature of 871° C. ^(†)Thepolymerization reaction was conducted at 100° C. in the presence of 5 mL1-hexene.

Examples 21-26

Examples 21-26 employed a Cr/silica catalyst as the supported catalystcomprising a hexavalent chromium species (1.0 wt. % Cr). The Cr/silicacatalysts were calcined at 650° C. in dry air (an oxidizing atmosphere)in order to convert the chromium to the hexavalent oxidation state. TheCr/silica catalyst had a BET surface area of 500 m²/g, a pore volume of1.6 mL/g, and an average particle size of 100 μm. Table III summarizesvarious catalyst reductions, catalyst productivity (grams ofpolyethylene per gram of catalyst), catalyst activity (grams ofpolyethylene per gram of catalyst per hour), and resultant polymer HMLI,I₁₀, and MI (g/10 min).

Using ethylene as the reductant, Examples 22-23 demonstrated comparablecatalyst activity to Example 21, but an unexpected improvement in meltindex potential. Also unexpectedly, the catalysts prepared with themethane reductant in sunlight resulted in a significant increase incatalyst activity, comparable melt index potential in ethylenehomopolymerization (Example 24), and superior melt index potential inethylene/1-hexene copolymerization (Example 26).

TABLE III Examples using Cr/Silica Catalysts Productivity Activity HLMII₁₀ MI Ex. Reductant Treatment Color (gPE/gCat) (g/g/h) (g/10 min) (g/10min) (g/10 min) 21 none none orange 2347 2996 4.8 0.82 0.009 22 10 psigsunlight blue/gray 1409 3019 6.1 1.22 — ethylene (×2) 6 h, 3 h 23 10psig sunlight blue/gray 1814 1432 7.4 1.53 0.033 ethylene (×2) 6 h, 3 h24 10 psig sunlight, green 2603 4222 4.0 0.66 — methane 6 h 25^(†) nonenone orange 2923 5480 2.4 0.21 0    26^(†) 10 psig sunlight, green 30947140 3.6 0.60 0.014 methane 6 h ^(†)The polymerization reaction wasconducted at 100° C. in the presence of 5 mL 1-hexene.

Examples 27-29

Certain examples above were conducted in sunlight or alternatively,under a fluorescent light emitting a spectrum of UV-Visible light. Inorder to evaluate which wavelength of light may be most effective atreducing the hexavalent species, Cr/silica-titania catalyst as describedabove was prepared by calcining for 3 h at 650° C., and treating thecalcined catalyst with a small amount (0.5 mL) of n-hexane in Example27. Samples of the catalyst underwent a reduction step as conductedabove, using one of a red LED (631 nm), blue LED (450 nm), or violet LED(392 nm) in glass bottles. The intensity and wavelength distribution ofeach light source is shown in FIG. 2. The color of each sample wasmonitored as an indicator of progress and efficiency of the reductionstep. Of the three, the blue light was by far the most effective,whereas the red light achieved almost nothing. The violet light was alsoeffective, but somewhat less so than the blue light. Since theseexperiments were conducted in glass containers that may absorb theshortest wavelengths of visible light, it is believed that a significantportion of the light emitted from the violet LED may have been absorbedby the glass.

In Example 28, IR reflectance spectra were obtained for a Cr/silicasample prepared as described above for Examples 21-26. As is shown inFIG. 3, the spectra demonstrate a strong absorbance at about 600 nmattributable to Cr(III) species, and another absorbance at about 340 nmattributable to Cr(VI) species. Thus, while not wishing to be bound bytheory, a more effective light source for catalyst reduction shouldinclude wavelengths less than 500 nm (e.g., compare blue light versusred light in FIG. 2).

For Example 29, perfluorohexane was evaluated as a reductant in a mannersimilar to benzene (Example 17), but did not result in a color change.Perfluorohexane contains only C—F and C—C bonds. While not wishing to bebound by theory, it is believed that compounds with C—H bonds are moresusceptible to oxidation under irradiation conditions.

Examples 30-45

Examples 30-45 were performed in the same manner as Examples 1-20 and,with the exception of Examples 36 and 42, used the same supportedchromium catalyst comprising silica-titania (2.5 wt. % Ti and 1.0 wt. %Cr). The Cr/silica-titania catalysts were calcined at 871° C. in dryair. Examples 36 and 42 used a 10% Cr/silica catalyst that was calcinedat 400° C. in dry air for 3 hr. Catalyst weights ranged from 0.04 to0.26 grams and polymerization reaction times ranged from 30 to 240 forExamples 30-45. Table IV summarizes the various catalyst reductions,catalytic activity, polymer molecular weight properties, polymerrheological characterization, and polymer MI, I₁₀, and HLMI (g/10 min).

Molecular weights and molecular weight distributions were obtained usinga PL-GPC 220 (Polymer Labs, an Agilent Company) system equipped with aIR4 detector (Polymer Char, Spain) and three Styragel HMW-6E GPC columns(Waters, MA) running at 145° C. The flow rate of the mobile phase1,2,4-trichlorobenzene (TCB) containing 0.5 g/L2,6-di-t-butyl-4-methylphenol (BHT) was set at 1 mL/min, and polymersolution concentrations were in the range of 1.0-1.5 mg/mL, depending onthe molecular weight. Sample preparation was conducted at 150° C. fornominally 4 hr with occasional and gentle agitation, before thesolutions were transferred to sample vials for injection. An injectionvolume of about 200 μL was used. The integral calibration method wasused to deduce molecular weights and molecular weight distributionsusing a Chevron Phillips Chemical Company's HDPE polyethylene resin,MARLEX® BHB5003, as the broad standard. The integral table of the broadstandard was pre-determined in a separate experiment with SEC-MALS. Mnis the number-average molecular weight, Mw is the weight-averagemolecular weight, Mz is the z-average molecular weight, My isviscosity-average molecular weight, and Mp is the peak molecular weight(location, in molecular weight, of the highest point of the molecularweight distribution curve).

Melt rheological characterizations were performed as follows.Small-strain (10%) oscillatory shear measurements were performed on anAnton Paar MCR 501 rheometer using parallel-plate geometry. Allrheological tests were performed at 190° C. The complex viscosity |η*|versus frequency (ω) data were then curve fitted using the modifiedthree parameter Carreau-Yasuda (CY) empirical model to obtain the zeroshear viscosity—η₀, characteristic viscous relaxation time—τ_(η), andthe breadth parameter—a (CY-a parameter). The simplified Carreau-Yasuda(CY) empirical model is as follows.

${{{\eta^{*}(\omega)}} = \frac{\eta_{0}}{\left\lbrack {1 + \left( {\tau_{\eta}\omega} \right)^{a}} \right\rbrack^{{({1 - n})}/a}}},$

wherein: |η*(ω)|=magnitude of complex shear viscosity;

-   -   η₀=zero shear viscosity;    -   τ_(η)=viscous relaxation time (Tau(η) in sec);    -   a=“breadth” parameter (CY-a parameter);    -   n=fixes the final power law slope, fixed at 2/11; and    -   ω=angular frequency of oscillatory shearing deformation.

Details of the significance and interpretation of the CY model andderived parameters can be found in: C. A. Hieber and H. H. Chiang,Rheol. Acta, 28, 321 (1989); C. A. Hieber and H. H. Chiang, Polym. Eng.Sci., 32, 931 (1992); and R. B. Bird, R. C. Armstrong and O. Hasseger,Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2nd Edition,John Wiley & Sons (1987); each of which is incorporated herein byreference in its entirety.

The long chain branches (LCBs) per 1,000,000 total carbon atoms of theoverall polymer were calculated using the method of Janzen and Colby (J.Mol. Struct., 485/486, 569-584 (1999), incorporated herein by referencein its entirety), from values of zero shear viscosity (determined fromthe Carreau-Yasuda (CY) model), and measured values of Mw obtained usinga Dawn EOS multiangle light scattering detector (Wyatt).

As shown in Table IV, the light reduction step was surprisinglyeffective for several different hydrocarbon reductants: methane, ethane,n-pentane, n-hexane, toluene, decalin, adamantane, and cyclohexane.Example 34 (34 min) and Example 35 (91 min) used differentpolymerization times, as did Example 43 (61 min) and Example 44 (37min). With the exception of Examples 36 and 42, the catalysts hadsurprising catalytic activity and melt index potential. Examples 30-33in Table IV demonstrate that catalyst treatment with light irradiationin the presence of a reductant reduces the long chain branching contentof the polymer produced, with an unexpected increase in the CY-aparameter.

As shown in Table IV, the polymers of Example 36 (0.26 g catalyst, 151min reaction time) and Example 42 (0.2 g catalyst, 240 min reactiontime), unexpectedly, had very broad molecular weight distributions(Mw/Mn in the 50-90 range) in combination with relatively high CY-avalues (0.29-0.33), and very low levels of LCBs (less than 3 per milliontotal carbon atoms). Also surprisingly, Table IV demonstrates that thepolymer of Example 40 (0.057 g catalyst, 57 min reaction time) had along high molecular weight tail, resulting in a Mz/Mw value in the 45-50range, despite have a relatively narrow molecular weight distribution(Mw/Mn less than 10), and substantially no LCBs.

TABLE IV Examples 30-45 Productivity Activity HLMI I₁₀ MI ExampleReductant Treatment Color (gPE/gCat) (g/g/h) (g/10 min) (g/10 min) (g/10min) CY-a 30 None None — — — — — 4.45 0.199 31 None None — — — — — 0.160.193 32 n-pentane Sunlight blue/gray 3188 3298 154 36.4 3.65 0.226 1 h33 n-hexane White light blue/gray 2251 2936 139 32.8 3.22 0.219 3 h 34toluene Blue light blue/black 1481 3065 203 46.8 3.6 0.199 1.5 h 35toluene Blue light blue/black 4235 3434 67 15.2 1.1 0.201 1.5 h 36n-pentane UV light black 238 107 3.4  0.5 — 0.294 3 h 37 10 psig UVlight dark blue/ 2267 2616 113 26.8 2.1 0.196 ethane 4 h gray 38 tolueneBlue light black 2312 2070 153 33.4 2.9 0.205 2.5 h 39 decalin Bluelight blue 1954 2345 198 34.7 4.2 0.204 2 h 40 adamantane Blue lightblue 2205 2646 166 30.6 3.5 0.200 2 h 41 cyclohexane Blue light blue2423 1069 47  7.3 0.8 0.210 2 h 42 None None dark red 262 81 0.5 — —0.327 43 methane Blue light green 2692 2884 157 36.5 3.4 0.229 2 h 44methane Blue light blue/gray 1024 1920 82 18.6 1.5 0.174 2 h 45 NoneNone orange 2668 2541 220 51.7 4.6 0.219 Mn Mw Mz η₀ τ_(η) J-C LCBExample Reductant (kg/mol) (kg/mol) (kg/mol) Mw/Mn Mz/Mw (Pa-sec) (sec)(per MM C) 30 None — — — — — — — — 31 None — — — — — — — — 32 n-pentane14.7 100 579 6.8 5.8 9.68E+03 0.016 8.8 33 n-hexane 9.8 102 962 10.3 9.51.24E+04 0.022 9.9 34 toluene 11.1 107 1060 9.6 9.9 1.24E+04 0.020 7.835 toluene 14.3 142 1129 9.9 8.0 4.42E+04 0.081 6.4 36 n-pentane 8.3 4162810 50.3 6.8 4.11E+06 50.4 2.2 37 ethane 9.6 120 1159 12.5 9.6 2.29E+040.034 7.7 38 toluene 14.7 101 760 6.9 7.5 1.26E+04 0.020 10.3 39 decalin14.4 108 835 7.5 7.7 9.74E+03 0.014 5.9 40 adamantane 17.2 166 8076 9.648.6 1.20E+04 0.015 <0.01 41 cyclohexane 15.7 162 1453 10.4 9.0 5.23E+040.111 4.2 42 None 6.3 557 3342 88.5 6.0 7.01E+06 49.6 1.2 43 methane13.8 104 726 7.5 7.0 8.20E+03 0.014 6.2 44 methane 14.3 130 1165 9.1 9.03.31E+04 0.024 7.4 45 None 12.9 102 843 7.9 8.3 8.01E+03 0.013 6.6

Examples 46-52

Examples 46-52 were performed to determine the extent of reduction ofthe hexavalent chromium and the average valence after reduction in arepresentative supported chromium catalyst. Table V summarizes theresults. Example 52 was a chromium/silica-titania catalyst containingapproximately 0.8 wt. % chromium and 7 wt. % titania, and having a BETsurface area of 530 m²/g, a pore volume of 2.6 mL/g, and an averageparticle size of 130 um, which was calcined in dry air at 850° C. for 3hr to convert chromium to the hexavalent oxidation state (orange). Thisconverted over 86 wt. % of the chromium into the hexavalent state. ForExamples 46-47, approximate 2 g samples of the catalyst of Example 52were separately charged to a glass reaction vessel and 0.5 mL of liquidisopentane was charged to the vessel. For Examples 48-49, about 1.5 atmof gaseous ethane was charged to the glass bottle. Then, the bottle wasplaced in a light-proof box under blue fluorescent light (approximately2 times the intensity expected from sunlight), and the bottle wascontinuously rotated so that all of the catalyst was exposed to thelight for 24 hr. The final catalyst color is noted in Table V.Afterward, into the bottle, along with the catalyst, was introducedabout 20 mL of a solution of 2 M H₂SO₄. To this was added 5 drops offerroin Fe(+3) indicator. This usually turned a blue-green colorindicating the presence of Fe(III) ions. Next, the solution was titratedto the ferroin endpoint (red color) using a solution of ferrous ammoniumsulfate, which had been previously calibrated by reaction with astandardized 0.1 M sodium dichromate solution. When the solution turnedred, the end point was signaled, and the titrant volume was recorded, tocalculate the oxidation capacity of the catalyst, expressed as wt. %Cr(VI) and as percent reduced, that is, the percent of the originalCr(VI) oxidative power that has been removed by the reduction treatment.The average valence was also computed by multiplying the percent reducedby +3 and subtracting that number from +6.

TABLE V Examples 46-52 Catalyst Cr(VI) Reduced Average Example ReductantTreatment Color (g) (wt. %) (wt. %) Valence 46 isopentane Blue lightblue 2.05 0.06 90.8 3.28 24 hr 47 isopentane Blue light blue 2.08 0.0690.9 3.27 24 hr 48 ethane Blue light olive 2.14 0.26 62.3 4.13 24 hrgreen 49 ethane Blue light olive 2.30 0.26 61.9 4.14 24 hr green 50 COBlue light blue 2.33 0.00 100 ≤3 2 hr green 51 CO CO reduction blue 2.520.00 100 ≤3 30 min - 350 ° C. 52 None None orange — 0.69 0 6.00

Of course, this treatment gives only an average oxidation state. Notethat although Table V lists the oxidative power measured as wt. %Cr(VI), in reality all of the chromium could be present in lower valencestates, such as Cr(IV) or Cr(V). Thus, the Cr(VI) value in Table V onlylists the maximum amount of Cr(VI) that could be present. More likely,the reduced catalysts have a combination of several valence states thatproduce the measured oxidative power. Note that some of the reducedchromium, and particularly those catalysts reduced with CO, may be inthe divalent state, which would not have been detected in this test,which stops in the trivalent state.

Example 52 demonstrates that the air-calcined chromium catalystcontained substantially most of its chromium (0.69/0.80=86 wt. %)present as Cr(VI), and it is this Cr(VI) amount that is being reduced inthe light treatment. Therefore, this amount of Cr(VI) serves as thestarting amount, which had an average valence of +6, and which serves asa reference, to which the reduced catalysts are then compared. Examples46-47 were reduced chromium catalysts with an average valence ofapproximately +3.3, with no more than 0.06 wt. % Cr(VI), and with lessthan 10 wt. % of the starting hexavalent chromium still remaining in thehexavalent oxidation state. Examples 48-49 were reduced chromiumcatalysts with an average valence of approximately +4.1, with no morethan 0.26 wt. % Cr(VI), and with less than 40 wt. % of the chromium inthe hexavalent oxidation state. For Examples 50-51, the catalyst wasreduced in CO with either blue light or elevated temperature, resultingin no oxidative power being measured (0 wt. % Cr(VI) in the table).Thus, the average valence must be no more than +3. But the catalyst thatwas CO-reduced by conventional means (Example 51) is known to have avalence of mostly Cr(II), which is not detected in this test.Accordingly, Examples 50 and 51 are listed as less than or equal to +3.Notably, this test cannot distinguish between Cr(II) and Cr(III)species, but there was no measurable amount of hexavalent chromium inExamples 50-51.

Examples 53-77

In Examples 53-77, Catalyst A was a Cr/silica catalyst containing 1 wt.% Cr, with a BET surface area of 500 m²/g, a pore volume of 1.6 mL/g,and an average particle size of 100 um. Prior to use, the catalyst wascalcined in air at 650° C. for 3 hr to form the chromium (VI)/silicacatalyst. Catalyst B was a Cr/silica-titania catalyst containing 1 wt. %Cr and 4.2 wt. % TiO₂, with a BET surface area of 500 m²/g, a porevolume of 2.5 mL/g, and an average particle size of 130 um. Prior touse, the catalyst was calcined in air at 870° C. for 3 hr to form thechromium (VI)/silica-titania catalyst. Catalyst C was a Cr/silicacontaining 10 wt. % Cr, with a BET surface area of 500 m²/g, a porevolume of 1.6 mL/g, and an average particle size of 100 um. Prior touse, the catalyst was calcined in air at 400° C. for 3 hr to form thechromium (VI)/silica catalyst. Catalyst D was a Cr/silica-titaniacontaining 1 wt. % Cr and 7.5 wt. % TiO₂, with a BET surface area of 550m²/g, a pore volume of 2.5 mL/g, and an average particle size of 130 um.Prior to use, the catalyst was calcined in air at 850° C. for 3 hr toform the chromium (VI)/silica-titania catalyst.

For the reductions of Examples 53-77, approximately two grams of thesupported chromium catalyst were first charged to an air-tight glasscontainer at 25° C., followed by the addition of the hydrocarbonreductant. The glass container was then exposed to a light source asnoted in Table VI below. For examples where the glass container wasexposed to sunlight, the container was taken outside and placed indirect sunlight, slowly rotating the container to ensure even exposureof the mixture of the supported chromium catalyst and the hydrocarbonreactant. For examples where the glass container was exposed toartificial light, the sample was placed in a box containing afluorescent light or a LED light. Reduction of the supported chromiumcatalysts was monitored by the presence of a color change. For eachcatalyst, the starting hexavalent supported chromium catalyst had anorange color which darkened significantly upon exposing the catalyst tolight in the presence of the hydrocarbon reactant, indicating reductionof the supported chromium catalyst starting material, and formation ofthe reduced chromium catalyst.

After the desired exposure time, the reduced chromium catalyst was mixedwith a hydrolysis agent to cleave the hydrocarbon-containing ligand fromthe reduced chromium catalyst. The hydrolysis agent used was water,methanol, ethanol, or trifluoroethanol, or a mixture thereof, and wasselected to not interfere with analysis of the reaction product (e.g.,methanol was not used as the hydrolysis agent when the reaction productafter hydrolysis could contain methanol).

A GC-MS procedure was used to analyze the reaction product, as follows.Gas chromatography was performed using an Agilent 7890B GC equipped withan all-purpose capillary column (Agilent J&W VF-5 ms, 30 m×0.25 mm×0.25μm). Approximate 0.5 μL sample aliquots were injected into a GC portheld at 250° C. using a split ratio of 10:1. The carrier gas wasultra-high purity helium and was electronically controlled throughoutthe run to a constant flow rate of 1.2 mL/min. Initial columntemperature was held at 50° C. for 5 min, ramped at 20° C./min to 250°C., and then held at 250° C. for 19 min. Spectral assignment was madevia mass correlation using an Agilent 5977B mass spectrometer connectedto the GC unit using electron ionization at 70 eV. The nominal massrange scanned was 14-400 m/z using a scan time of 0.5 sec. Nominaldetector voltage used was 1200 V.

Table VI summarizes the results of Examples 53-77, and lists thespecific chromium catalyst, the hydrocarbon reductant, the lighttreatment, and an analysis of the reaction product after hydrolysis.Examples 53-58 demonstrate the unexpected finding that the—O-Hydrocarbon group on the chromium catalyst after reduction was a—O-Methane group; the reaction product after hydrolysis to cleave thehydrocarbon-containing ligand from the catalyst was predominantlymethanol. Similar surprising results were found for chromium catalystswith a —O-n-Pentane group (pentanol hydrolysis product), a —O-n-Hexanegroup (hexanol hydrolysis product), and a —O-Cyclohexane group(cyclohexanol hydrolysis product), among others. Likewise, a chromiumcatalyst with a —O-Toluene group (benzaldehyde hydrolysis product) alsowas produced. In Example 63, toluene was converted into benzaldehyde (noalcohol), but in Example 68, toluene was converted into a variety ofalcohol and carbonyl products; the only difference between theseexamples was the irradiation exposure time. When the reductant wasdichloromethane, no alcohol or carbonyl hydrolysis product was noted.However, it is believed that other halogenated hydrocarbon materialswould form —O-Halogenated hydrocarbon groups on the chromium catalyst,such as tetrafluoroethane (see Examples 15-16).

TABLE VI Summary of Examples 53-77. Light Example Catalyst Reductanttreatment Reaction product after hydrolysis 53 A 1.7 atm methane 10 hrsunlight 83% methanol, 17% ethanol 54 A 1.7 atm methane 3 hr sunlight61% methanol, 34% ethanol, 3% propanoic acid, 2% acetic acid 55 B 1.7atm methane 10 hr sunlight 55% ethanol, 45% methanol 56 A 1.7 atmmethane 6 hr sunlight no carboxylates detected, alcohols not analyzed 57B 1.7 atm methane 6 hr sunlight 100% methanol, no carboxylates 58 A 1.7atm methane 6 hr sunlight 100% methanol 59 A 1.7 atm ethylene 3 hrsunlight 42% methanol, 56% formic acid, 2% acetic acid 60 B 1.7 atmethylene 3 hr sunlight 76% formic acid, 21% methanol, 2% acetic acid, 1%ethanol 61 B 0.5 mL n- 1 hr sunlight 2-pentanol > 2-pentanone >1-pentanol >> 3-pentanone pentane 62 B 0.5 mL n- 3 hr white 2-hexanol >3-hexanol > 1-hexanol > 2-hexanone > 3-hexanone > hexane fluorescentlight 1-hexanone > 1-butanol > C7&C18 oxygenates >> hexanal 63 B 0.5 mLtoluene 1.5 hr blue benzaldehyde fluorescent light 64 C 0.5 mL n- 3 hrUV 2-pentanone > 2-pentanol > 3-pentanone >> 1-pentanone = pentanefluorescent light enones = enols 65 D 0.5 mL n- 3 hr blue 2-pentanol >2-pentanone > 1-pentanol >> 3-pentanone pentane fluorescent light 66 D0.5 mL n- 3 hr blue 2-hexanol > 3-hexanol > 1-hexanol > 2-hexanone > 3-hexane fluorescent light hexanone > 1-hexanone > 1-butanol > C7&C18oxygenates >> hexanal, no alkanes 67 D 0.5 mL n- 3 hr blue 2-pentanol >1-pentanol > 2-pentanone > C7-C18 oxygenates, pentane fluorescent lightno alkanes 68 D 0.5 mL toluene 3 hr blue benzaldehyde > benzyl alcohol >benzophenone = 4-Me fluorescent light benzophenone => 2-Me Phenol = 2-Mebenzophenone = 3- Me Benzophenone > 4-Me Phenol > 3-Me Benzaldehyde 69 D10% Cr n- 18 hr blue 2-pentanone > 2-pentanol > 3-pentanone >>1-pentanone = c7 pentane fluorescent light enones = c7 enols 70 D 0.5 mL3 hr blue LED cyclohexanol >= cyclohexanone >> cyclohexenone >> maybecyclohexane light C14&C18 oxygenates 71 D 0.5 mL decalin 3 hr blue LEDdecahydronaphthalene (C10H18) (two isomers) > lighttetrahydronaphthalene (C10H12) >> various bicyclic C10 alcohols (withthe OH at different positions) 72 D 0.5 mL 3 hr blue LED adamantanol >andamantanone >+ another isomer of adamantane light adamantanol 73 D 0.5mL 7 hr blue 4 isomers of C5-OH, similar size, only a trace of ketoneisopentane fluorescent light 74 D 0.5 mL n- 7 hr blue 2-pentanol >another pentanol, no ketones pentane fluorescent light 75 D 0.5 mL 7 hrblue cyclopentanol >> likely dimer ethers C10H20O2 cyclohexanefluorescent light 76 D 0.5 mL n- 7 hr blue 7 isomers of dodecene, andtrace of C6H10O3 (an aldehyde at hexane fluorescent light one end and anester at the other) 77 D 0.5 mL dichloro 7 hr blue nothing identifiedmethane fluorescent light

Examples 78-94

Table VII summarizes Examples 78-92. In these examples, Catalyst A was aCr/silica-titania containing 2.5 wt. % Ti and 1 wt. % Cr, with anaverage particle size of 130 um, a pore volume 2.5 mL/g, and a BETsurface area of 500 m²/g. Prior to use, the catalyst was calcined in dryair for 3 hr at 871° C. to form a chromium (VI)/silica-titania catalyst.Catalyst B was a light reduced catalyst prepared by exposing Catalyst Ato 1.5 atm of deuterated propylene (C₃D6) under sunlight for 2 hr at 25°C. Excess deuterated propylene was then purged with N₂. Catalyst C was alight reduced catalyst prepared by exposing Catalyst A to 0.25 mL/g ofdeuterated n-hexane (C₆D14) under sunlight for 2 hr at 25° C. Catalyst Dwas a light reduced catalyst prepared by exposing Catalyst A to 0.25mL/g of deuterated cyclohexane (C₆D12) under blue fluorescent light for2 hr at 25° C. Catalyst E was a light reduced catalyst prepared byexposing Catalyst A to 0.25 mL/g of deuterated toluene (C₇D8) under bluefluorescent light for 2 hr at 25° C. Catalyst F was a CO-reducedcatalyst prepared by flushing Catalyst A at 350° C. with N₂ for 15 min,then treating with 100% CO for 30 min at 350° C., and flushing againwith N₂ for 15 min, and followed by cooling at 25° C. and storing underN₂. In Table VII, Catalyst F was subsequently subjected to the treatmentshown in Table VII for 10-15 min prior to polymerization.

Polymerization experiments for Examples 78-94 utilized approximately 2 gof catalyst, a reaction time in the 10-25 minute range (to produce 1-2grams of polymer per gram of catalyst), an ethylene pressure of 24-30psig (normal unlabeled ethylene), and a polymerization temperature of50° C. (unless noted otherwise). Isopropanol or ethanol was used toquench the reaction.

For NMR analysis, the samples were prepared in 10 mm NMR tube. About 0.3g of selectively deuterium-labeled polyethylene samples was dissolved ina mixture of 2.5 mL 1,2,4-trichlorobenzene (TCB) and 1.20 g of1,4-dichlorobenzene-d₄ (DCB-d₄) for ¹H and ¹³C NMR data collection. Forsolution-state deuterium (²H) NMR data collection, about 0.3 g of thepolyethylene samples and the model compound were dissolved in 2.5 mL ofnon-deuterated TCB solvent.

The sample and the solvent (or solvent mixture) were heated in a heatingblock at 130° C. for 4-5 hr. The mixture was occasionally stirred with astainless-steel stirrer to ensure homogeneous mixing. The resultingsolution was then left overnight (for 15-16 hr) in the heating block at112° C. to ensure complete disentanglement of the polymer chains. Thefinal concentrations of the resulting solutions were about 5-7 wt. %.

The NMR data were collected in a 500 MHz NMR instrument comprised of a500 MHz Oxford magnet and Bruker's Avance III HD console. A 10 mm BBOprobe fitted with z-gradient was used for ¹H, ²H and ¹³C NMR datacollection. The deuterium lock channel of the instrument was used for ²HNMR data collection. All the NMR data were collected at 125° C. and thesample was equilibrated at 125° C. for 15 min before the start of dataacquisition. The data were collected and processed with Bruker's Topspinsoftware (v. 3.2).

The ¹H NMR data were collected with standard pulse sequence using thestandard parameter set including: a 7.4 μsec 90° pulse width, a 7.5 kHzspectral window, 5.0 sec relaxation delay, and 5.0 sec acquisition time.1024 transients were averaged to obtain enough signal-to-noise ratio(SNR) to detect the signals originated from terminal olefins. The datawas zero filled with 131 k data points and exponentially weighted with0.30 Hz line-broadening before Fourier transformation. The spectrum wasreferenced with the residual proton peak of DCB-d₄ solvent (δ˜7.16 ppm).

The ²H NMR (deuterium) data were collected with standard pulse sequenceusing the standard parameter set including: a 225 μsec 90° pulse width,a 1.15 kHz spectral window, 2.0 sec relaxation delay, and 0.99 secacquisition time. 16 k transients were collected and averaged to obtainenough SNR to detect the methyl signal. The data was zero filled with 8k data points and exponentially weighted with 2.0 Hz line-broadeningbefore Fourier transformation. The spectrum was referenced with thenatural abundance deuterium peak of non-deuterated TCB solvent (thechemical shift of the central peak of the triplet is calibrated at δ˜7.2ppm).

The ¹³C NMR spectra of the polyethylene samples were collected withstandard pulse program using the standard parameter set including: a13.0 μsec 90° pulse width, a 21.7 kHz spectral window, 7.0 secrelaxation delay, and 3.0 sec acquisition time. 8 k transients werecollected in an overnight experiment and full NOE was exploited duringdata collection to improve the SNR at a reasonable amount of time. Thedata was zero filled with 2 times of time-domain (TD) data points andexponentially weighted with a 1.0 Hz line-broadening before Fouriertransformation.

The ²H NMR data in Table VII demonstrates, unexpectedly, that thereductant used in Catalysts B-E was incorporated into the polymer as aterminal or end group. Likewise, the adjuvant material of CO-reducedCatalyst F, also unexpectedly, was incorporated into the polymer as aterminal or end group. Thus, terminal alkane, cyclic alkane, andaromatic end groups were incorporated into an ethylene polymer.

The NMR data in Table VII also demonstrates ethylene homopolymers with asurprising combination of a relatively high number of methyl short chainbranches (SCB's) and a relatively low number of butyl SCB's per 1000total carbon atoms. The homopolymers of Examples 78, 82-84, 86, and90-91 have at least 3.5 methyl SCB's per 1000 total carbon atoms andless than 0.6 butyl SCB's. Moreover, these homopolymers have ratios ofvinyl chain ends to saturated chain ends (vinyl/saturated) per 1000total carbon of less than 0.1 (and zero in most cases), which isparticularly unexpected, given that conventional chromium-based polymersoften have vinyl/saturated ratios between 0.5 and 1.0.

FIG. 4 illustrates the molecular weight distributions of the polymers ofExamples 88-89 and 93-94, and Table VIII summarizes certain molecularweight features. The adjuvant used in Example 88 was n-hexane, whileExample 89 used toluene, and Example 93 used benzene (prepared similarlyto Example 89). Example 94 was a control experiment in which no adjuvantwas used. As shown in FIG. 4 and Table VIII, the polymer of Example 89(toluene adjuvant) had a surprising combination of a relatively largeamount of the polymer having a molecular weight greater than 1,000,000g/mol (over 6 wt. %) and a relatively large amount of the polymer havinga molecular weight less than 1000 g/mol (over 4 wt. %). Note also thelarge Mw/Mn of 47 shown in Table VIII.

TABLE VII Summary of Examples 78-92. Starting Polymerization ²H NMRExample Catalyst Valence Other Treatment Temp Deuterium Signals** 78 BCr+6 None  0° C. CD₂, CD₃, CD 79 C Cr+6 None 50° C. CD, CD₂, CD₃,D-allyl, D-term-vinyl 80 D Cr+6 None 50° C. CD, CD₂, CD₃, D-allyl, lessD-term-vinyl 81 E Cr+6 None 80° C. Aromatics, CD₂, CD₃, maybe allyl 82 FCr+2 C₂D₄ −78° C. 80° C. CD₃, CD₂ 83 F Cr+2 C₂D₄ 0° C.  0° C. CD₃, CD₂84 F Cr+2 C₂D₄ −78° C. 80° C. CD₃, CD₂ 85 F Cr+2 C₂D₄ −78° C.  0° C.CD₂, CD₃ 86 F Cr+2 C₃D₆ −78° C. 50° C. CD₃, CD₂, CD, D-vinylidene,D-vinylene 87 F Cr+2 C₃D₆ −78° C. 50° C. CD₃, CD₂, CD, D-vinylidene,D-vinylene 88 F Cr+2 C₆D₁₄ 25° C. 50° C. CD₃, CD₂- 89 F Cr+2 C₇D₈ 25° C.50° C. Aromatics, CD₂, maybe D-allyl 90 F Cr+2 C₂D₄ 0° C.  0° C. N/A -ethanol quench 91 B* Cr+6 None  0° C. N/A 92 F Cr+2 C₃D₆ 25° C. 25° C.N/A Mn Mw Mz Example (kg/mol) (kg/mol) (kg/mol) Mw/Mn Mz/Mw 78 10.1 50146 4.9 2.9 79 11.2 78 342 7.0 4.4 80 8.3 50.2 224 6.0 4.5 81 11.7 66211 5.7 3.2 82 10.6 54 173 5.0 5.4 83 16.9 129 625 7.6 4.9 84 9.9 76 2507.7 7.3 85 12.7 196 1225 15.4 6.3 86 12.1 59 277 4.9 4.7 87 17.1 1991075 11.6 5.4 88 8.9 100 628 11.2 6.3 89 5.5 258 2449 47.1 9.5 90 14.0107 597 7.6 5.6 91 9.3 45 160 4.9 3.5 92 11.2 78 342 7.0 4.4 VinylSaturated Vinyl/ Methyls Ethyls Butyls Example (1000 TC) (1000 TC)Saturated (1000 TC) (1000 TC) (1000 TC) 78 0 6.46 0.00 5.70 1.20 0.00 79— — — — — — 80 0.86 3.94 0.22 0.60 0.00 0.00 81 0 5.95 0.00 2.85 0.100.00 82 0 5.18 0.00 5.65 1.80 0.10 83 0 2.33 0.00 4.05 3.20 0.30 84 03.82 0.00 9.05 0.00 0.00 85 0 1.52 0.00 3.10 1.15 0.00 86 0.23 4.55 0.056.00 1.80 0.00 87 0.63 1.78 0.81 2.10 0.20 0.00 88 — — — — — — 89 — — —— — — 90 0 2.40 0.00 4.85 3.00 0.00 91 0 6.39 0.00 5.00 1.15 0.00 92 0.33.69 0.08 0.05 0.15 0.00 B* - Example 91 was performed similarly toExample 78, except deuterated ethylene was used instead of propylene.**D-allyl: CH₂ = CH-CD-; D-terminal vinyl: CD₂ = CD-; D-vinylidene: =CD₂; D-vinylene: -CD = CD-

TABLE VIII Examples 88-89 and 93-94. Example 88 89 93 94 Adjuvanttreatment n-Hexane Toluene Benzene Control Weight percentage having amolecular weight less than 1000 g/mol 1.5 4.2 1.4 0.2 10,000 g/mol 23.130.9 24.6 14.3 100,000 g/mol 76.0 70.3 74.4 74.6 1,000,000 g/mol 99.093.6 97.7 99.2 Weight percentage having a molecular weight greater than1,000,000 g/mol 1.0 6.4 2.3 0.8 100,000 g/mol 24.0 29.7 25.6 25.4 10,000g/mol 76.9 69.1 75.4 85.7 1000 g/mol 98.5 95.8 98.6 99.8 Weightpercentage having a molecular weight in the range of 1000 to 10,000g/mol 21.6 26.7 23.2 14.1 10,000 to 100,000 g/mol 52.9 39.5 49.7 60.3100,000 to 1 million g/mol 23.0 23.3 23.3 24.6 10,000 to 1 million g/mol75.9 62.8 73.1 84.9 100,000 to 1 million g/mol 23.0 23.3 23.3 24.6 Lessthan <3162 g/mol 8.6 15.2 7.9 3.2 Lowest and highest measured molecularweights (g/mol) Lowest MW 292 231 398 744 Highest MW 4,604,156 9,812,5077,176,951 3,718,348

The invention is described above with reference to numerous aspects andspecific examples. Many variations will suggest themselves to thoseskilled in the art in light of the above detailed description. All suchobvious variations are within the full intended scope of the appendedclaims. Other aspects of the invention can include, but are not limitedto, the following (aspects are described as “comprising” but,alternatively, can “consist essentially of” or “consist of”):

Aspect 1. A supported chromium catalyst comprising:

a solid support; and from about 0.01 to about 20 wt. % chromium, basedon the weight of the catalyst; wherein:

the chromium has an average valence of less than or equal to about 5.25;and

at least one bonding site on the chromium has a ligand characterized byone of the following formulas: —O-Hydrocarbon group or —O-Halogenatedhydrocarbon group.

Aspect 2. The catalyst defined in aspect 1, wherein the molar ratio ofthe hydrocarbon group to chromium is in any suitable range or any rangedisclosed herein, e.g., from about 0.25:1 to about 2:1, from about 0.5:1to about 2:1, from about 0.5:1 to about 1.5:1, from about 0.75:1 toabout 1.75:1, or from about 0.75:1 to about 1.25:1.

Aspect 3. The catalyst defined in aspect 1 or 2, wherein the supportedchromium catalyst comprises any suitable amount of chromium or an amountin any range disclosed herein, e.g., from about 0.01 to about 10 wt. %,from about 0.05 to about 15 wt. %, from about 0.1 to about 15 wt. %,from about 0.2 to about 10 wt. %, from about 0.1 to about 5 wt. %, orfrom about 0.5 to about 2.5 wt. % of chromium, based on the weight ofthe catalyst.

Aspect 4. The catalyst defined in any one of the preceding aspects,wherein the supported chromium catalyst comprises any suitable amount ofchromium in an oxidation state of +5 or less, or an amount in any rangedisclosed herein, e.g., from about 0.01 to about 20 wt. %, from about0.01 to about 10 wt. %, from about 0.05 to about 15 wt. %, from about0.1 to about 15 wt. %, from about 0.2 to about 10 wt. %, from about 0.1to about 5 wt. %, or from about 0.5 to about 2.5 wt. % of chromium in anoxidation state of +5 or less, based on the weight of the catalyst.

Aspect 5. The catalyst defined in any one of the preceding aspects,wherein the catalyst comprises chromium having an average valence ofless than or equal to about 5.25, less than or equal to about 5, lessthan or equal to about 4.75, less than or equal to about 4.5, less thanor equal to about 4.25, or less than or equal to about 4.

Aspect 6. The catalyst defined in any one of the preceding aspects,wherein the supported chromium catalyst comprises (from 0 wt. %, fromabout 0.5 wt. %, from about 1 wt. %, or from about 2 wt. % to) to lessthan or equal to about 75 wt. %, less than or equal to about 50 wt. %,less than or equal to about 40 wt. %, or less than or equal to about 30wt. % of chromium (VI), based on the total amount of chromium.

Aspect 7. The catalyst defined in any one of aspects 1-6, wherein thesolid support comprises any suitable solid oxide or any solid oxidedisclosed herein, e.g., silica, alumina, silica-alumina, silica-coatedalumina, aluminum phosphate, aluminophosphate, heteropolytungstate,titania, zirconia, magnesia, boria, zinc oxide, silica-titania,silica-zirconia, alumina-titania, alumina-zirconia, zinc-aluminate,alumina-boria, alumina borate, silica-boria, aluminophosphate-silica,titania-zirconia, or any combination thereof.

Aspect 8. The catalyst defined in any one of aspects 1-6, wherein thesolid support comprises silica, silica-alumina, silica-coated alumina,silica-titania, silica-titania-magnesia, silica-zirconia,silica-magnesia, silica-boria, aluminophosphate-silica, alumina, aluminaborate, or any combination thereof.

Aspect 9. The catalyst defined in any one of aspects 1-6, wherein thesolid support comprises a chemically-treated solid oxide comprising asolid oxide (e.g., as in aspect 7 or 8) treated with anelectron-withdrawing anion.

Aspect 10. The catalyst defined in aspect 9, wherein theelectron-withdrawing anion comprises sulfate, bisulfate, fluoride,chloride, bromide, iodide, fluorosulfate, fluoroborate, phosphate,fluorophosphate, trifluoroacetate, triflate, fluorozirconate,fluorotitanate, phospho-tungstate, tungstate, molybdate, or anycombination thereof.

Aspect 11. The catalyst defined in aspect 9 or 10, wherein thechemically-treated solid oxide contains from about 1 to about 30 wt. %,from about 2 to about 20 wt. %, from about 2 to about 15 wt. %, fromabout 3 to about 12 wt. %, or from 4 to 10 wt. %, of theelectron-withdrawing anion, based on the total weight of thechemically-treated solid oxide.

Aspect 12. The catalyst defined in any one of aspects 1-6, wherein thesolid support comprises a chemically-treated solid oxide comprisingfluorided alumina, chlorided alumina, bromided alumina, sulfatedalumina, fluorided silica-alumina, chlorided silica-alumina, bromidedsilica-alumina, sulfated silica-alumina, fluorided silica-zirconia,chlorided silica-zirconia, bromided silica-zirconia, sulfatedsilica-zirconia, fluorided silica-titania, fluorided silica-coatedalumina, fluorided-chlorided silica-coated alumina, sulfatedsilica-coated alumina, phosphated silica-coated alumina, or anycombination thereof.

Aspect 13. The catalyst defined in any one of aspects 1-6, wherein thecatalyst comprises chromium/silica, chromium/silica-titania,chromium/silica-titania-magnesia, chromium/silica-alumina,chromium/silica-coated alumina, chromium/aluminophosphate,chromium/alumina, chromium/alumina borate, or any combination thereof.

Aspect 14. The catalyst defined in any one of aspects 1-6, wherein thecatalyst comprises chromium/silica-titania, and the supported catalystcomprises any suitable amount of titanium or an amount in any rangedisclosed herein, e.g., from about 0.1 to about 20 wt. %, from about 0.5to about 15 wt. %, from about 1 to about 10 wt. %, or from about 1 toabout 6 wt. %, based on the weight of the catalyst.

Aspect 15. The catalyst defined in any one of aspects 1-6, wherein thecatalyst comprises chromium/sulfated alumina, chromium/fluoridedalumina, chromium/fluorided silica-alumina, chromium/fluoridedsilica-coated alumina, or any combination thereof.

Aspect 16. The catalyst defined in any one of aspects 1-6, wherein thecatalyst comprises a chromium supported zeolite.

Aspect 17. The catalyst defined in aspect 16, wherein the solid supportcomprises a medium pore zeolite, a large pore zeolite, or a combinationthereof.

Aspect 18. The catalyst defined in aspect 16, wherein the solid supportcomprises a ZSM-5 zeolite, a ZSM-11 zeolite, a EU-1 zeolite, a ZSM-23zeolite, a ZSM-57 zeolite, an ALPO4-11 zeolite, an ALPO4-41 zeolite, aFerrierite framework type zeolite, or a combination thereof.

Aspect 19. The catalyst defined in aspect 16, wherein the solid supportcomprises an L-zeolite, a Y-zeolite, a mordenite, an omega zeolite,and/or a beta zeolite.

Aspect 20. The catalyst defined in any one of aspects 16-19, wherein thesolid support comprises a zeolite and any suitable amount of binder oran amount in any range disclosed herein, e.g., from about 3 wt. % toabout 35 wt. %, or from about 5 wt. % to about 30 wt. % binder, based onthe weight of the catalyst.

Aspect 21. The catalyst defined in any one of the preceding aspects,wherein the catalyst has any suitable pore volume (total) or a porevolume (total) in any range disclosed herein, e.g., from about 0.1 toabout 5 mL/g, from about 0.15 to about 5 mL/g, from about 0.1 to about 3mL/g, or from about 0.15 to about 2 mL/g.

Aspect 22. The catalyst defined in any one of the preceding aspects,wherein the catalyst has any suitable BET surface area or a BET surfacearea in any range disclosed herein, e.g., from about 50 to about 2000m²/g, from about 50 to about 700 m²/g, from about 50 to about 400 m²/g,from about 100 to about 1200 m²/g, or from about 150 to about 525 m²/g.

Aspect 23. The catalyst defined in any one of the preceding aspects,wherein the catalyst has any suitable average (d50) particle size or anaverage (d50) particle size in any range disclosed herein, e.g., fromabout 10 to about 500 microns, from about 25 to about 250 microns, orfrom about 20 to about 100 microns.

Aspect 24. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is a saturated or unsaturated, linear or branched,aliphatic hydrocarbon group.

Aspect 25. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is an aromatic group.

Aspect 26. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is a linear alkane group, a branched alkane group, ora cyclic alkane group.

Aspect 27. The catalyst defined in any one of aspects 1-23, wherein analkoxy group is bonded to the chromium.

Aspect 28. The catalyst defined in any one of aspects 1-23, wherein anaryloxy group is bonded to the chromium.

Aspect 29. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is any suitable carbon number hydrocarbon group or anycarbon number hydrocarbon group disclosed herein, e.g., a C₁ to C₃₆hydrocarbon group, a C₁ to C₁₈ hydrocarbon group, a C₁ to C₁₂hydrocarbon group, or a C₁ to C₈ hydrocarbon group.

Aspect 30. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is a methane group, an ethane group, a propane group,a butane (e.g., n-butane or isobutane) group, a pentane (e.g.,n-pentane, neopentane, or isopentane) group, a hexane group, a heptanegroup, an octane group, a nonane group, a decane group, an undecanegroup, a dodecane group, a tridecane group, a tetradecane group, apentadecane group, a hexadecane group, a heptadecane group, or anoctadecane group.

Aspect 31. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is a methane group, an ethane group, a propane group,a n-butane group, an isobutane group, a n-pentane group, a neopentanegroup, an isopentane group, a n-hexane group, a n-heptane group, an-octane group, a n-decane group, or a n-dodecane group.

Aspect 32. The catalyst defined in any one of aspects 1-23, wherein thehydrocarbon group is a benzene group, a toluene group, an ethylbenzenegroup, a xylene group, or a mesitylene group.

Aspect 33. An ethylene polymer having (or characterized by):

a Mw in a range from about 100,000 to about 400,000 g/mol;

at least about 2 wt. % of the polymer having a molecular weight greaterthan 1,000,000 g/mol; and

at least about 1.5 wt. % of the polymer having a molecular weight lessthan 1000 g/mol.

Aspect 34. The polymer defined in aspect 33, wherein the ethylenepolymer has a Mn in any range disclosed herein, e.g., from about 3,000to about 10,000 g/mol, from about 4,000 to about 9,000 g/mol, from about4,000 to about 8,000 g/mol, from about 4,000 to about 7,000 g/mol, orfrom about 5,000 to about 6,000 g/mol.

Aspect 35. The polymer defined in aspect 33 or 34, wherein the ethylenepolymer has a Mw in any range disclosed herein, e.g., from about 100,000to about 300,000 g/mol, from about 150,000 to about 400,000 g/mol, fromabout 200,000 to about 400,000 g/mol, or from about 200,000 to about300,000 g/mol.

Aspect 36. The polymer defined in any one of aspects 33-35, wherein theethylene polymer has a Mz in any range disclosed herein, e.g., fromabout 1,500,000 to about 4,000,000 g/mol, from about 2,000,000 to about3,500,000 g/mol, or from about 2,000,000 to about 3,000,000 g/mol.

Aspect 37. The polymer defined in any one of aspects 33-36, wherein theethylene polymer has a Mp in any range disclosed herein, e.g., fromabout 10,000 to about 60,000 g/mol, from about 10,000 to about 50,000g/mol, from about 10,000 to about 40,000 g/mol, or from about 15,000 toabout 30,000 g/mol.

Aspect 38. The polymer defined in any one of aspects 33-37, wherein theethylene polymer has a ratio of Mw/Mn in any range disclosed herein,e.g., from about 30 to about 80, from about 35 to about 75, from about35 to about 60, from about 40 to about 55, or from about 45 to about 50

Aspect 39. The polymer defined in any one of aspects 33-38, wherein theethylene polymer has a ratio of Mz/Mw in any range disclosed herein,e.g., from about 6 to about 13, from about 8 to about 11, from about 8.5to about 10.5, or from about 9 to about 10.

Aspect 40. The polymer defined in any one of aspects 33-39, wherein anamount of the ethylene polymer in any range disclosed herein, e.g., fromabout 2 to about 10 wt. %, from about 3 to about 10 wt. %, from about 4to about 9 wt. %, from about 5 to about 9 wt. %, or from about 5 toabout 8 wt. %, has a molecular weight greater than 1,000,000 g/mol.

Aspect 41. The polymer defined in any one of aspects 33-40, wherein anamount of the ethylene polymer in any range disclosed herein, e.g., fromabout 1.5 to about 8 wt. %, from about 2 to about 7 wt. %, from about 3to about 6 wt. %, from about 3.5 to about 5 wt. %, or from about 4 toabout 4.5 wt. %, has a molecular weight less than 1000 g/mol.

Aspect 42. The polymer defined in any one of aspects 33-41, wherein anamount of the ethylene polymer in any range disclosed herein, e.g., fromabout 8 to about 20 wt. %, from about 10 to about 20 wt. %, from about12 to about 18 wt. %, from about 13 to about 17 wt. %, or from about 14to about 16 wt. %, has a molecular weight less than 3162 g/mol.

Aspect 43. The polymer defined in any one of aspects 33-42, wherein anamount of the ethylene polymer in any range disclosed herein, e.g., fromabout 53 to about 73 wt. %, from about 55 to about 70 wt. %, from about58 to about 68 wt. %, or from about 61 to about 65 wt. %, has amolecular weight in the 10,000 to 1,000,000 g/mol range.

Aspect 44. The polymer defined in any one of aspects 33-43, wherein theethylene polymer has a highest molecular weight detected in any rangedisclosed herein, e.g., at least about 5,000,000 g/mol, at least about6,000,000 g/mol, at least about 7,000,000 g/mol, or at least about8,000,000 g/mol.

Aspect 45. An ethylene homopolymer having (or characterized by):

a number of methyl short chain branches (SCB's) in a range from about3.5 to about 15 per 1000 total carbon atoms;

a number of butyl short chain branches (SCB's) of less than or equal toabout 0.6 per 1000 total carbon atoms; and

a ratio of Mw/Mn in a range from about 4 to about 10.

Aspect 46. The homopolymer defined in aspect 45, wherein the number ofmethyl SCB's is in any range disclosed herein, e.g., from about 3.5 toabout 12, from about 3.5 to about 10.5, from about 4 to about 12, fromabout 4 to about 10, from about 4.5 to about 10, or from about 5 toabout 10 methyl SCB's per 1000 total carbon atoms.

Aspect 47. The homopolymer defined in aspect 45 or 46, wherein thenumber of butyl SCB's is in any range disclosed herein, e.g., less thanor equal to about 0.5, less than or equal to about 0.4, less than orequal to about 0.3, or less than or equal to about 0.2 butyl SCB's per1000 total carbon atoms.

Aspect 48. The homopolymer defined in any one of aspects 45-47, whereinthe ratio of Mw/Mn is in any range disclosed herein, e.g., from about 4to about 9, from about 4 to about 8.5, from about 4 to about 8, fromabout 4.5 to about 10, from about 4.5 to about 8.5, or from about 5 toabout 9.

Aspect 49. The homopolymer defined in any one of aspects 45-48, whereinthe homopolymer has a ratio of Mz/Mw in any range disclosed herein,e.g., from about 2.5 to about 7, from about 2.5 to about 6, from about 3to about 7, or from about 3 to about 6.

Aspect 50. The homopolymer defined in any one of aspects 45-49, whereinthe homopolymer has a Mw in any range disclosed herein, e.g., from about30,000 to about 200,000 g/mol, from about 30,000 to about 140,000 g/mol,from about 35,000 to about 150,000 g/mol, or from about 40,000 to about135,000 g/mol.

Aspect 51. The homopolymer defined in any one of aspects 45-50, whereinthe homopolymer has ratio of vinyl chain ends to saturated chain ends(vinyl/saturated) per 1000 total carbon atoms in any range disclosedherein, e.g., less than or equal to about 1, less than or equal to about0.5, less than or equal to about 0.3, or less than or equal to about0.1.

Aspect 52. The homopolymer defined in any one of aspects 45-51, whereinthe homopolymer has a number of ethyl SCB's is in any range disclosedherein, e.g., from about 0.8 to about 5, from about 1 to about 5, fromabout 0.8 to about 4, from about 1 to about 4, from about 0.8 to about3.5, from about 1 to about 3.5, or from about 1.5 to about 3.5 ethylSCB's per 1000 total carbon atoms.

Aspect 53. The homopolymer defined in any one of aspects 45-52, whereinthe homopolymer has a density in any range disclosed herein, e.g., fromabout 0.93 to about 0.96 g/cm³, from about 0.93 to about 0.955 g/cm³,from about 0.935 to about 0.955 g/cm³, from about 0.935 to about 0.950g/cm³, or from about 0.938 to about 0.948 g/cm³.

Aspect 54. The homopolymer defined in any one of aspects 45-53, whereinthe homopolymer contains, independently, less than 0.1 ppm (by weight),less than 0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm, of nickeland iron.

Aspect 55. The homopolymer defined in any one of aspects 45-54, whereinthe homopolymer contains, independently, less than 0.1 ppm (by weight),less than 0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm, oftitanium, zirconium, and hafnium.

Aspect 56. An ethylene polymer comprising:

a terminal branched alkane group;

a terminal cyclic alkane group;

a terminal aromatic group; or a terminal halogenated hydrocarbon group.

Aspect 57. The polymer defined in aspect 56, wherein the ethylenepolymer comprises an ethylene homopolymer.

Aspect 58. The polymer defined in aspect 56, wherein the ethylenepolymer comprises an ethylene/α-olefin copolymer.

Aspect 59. The polymer defined in aspect 56, wherein the ethylenepolymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexenecopolymer, and/or an ethylene/1-octene copolymer.

Aspect 60. The polymer defined in aspect 56, wherein the ethylenepolymer comprises an ethylene/1-hexene copolymer.

Aspect 61. The polymer defined in any one of aspects 56-60, wherein thebranched alkane group is any carbon number branched alkane groupdisclosed herein, e.g., a C₄ to C₃₆ branched alkane group, a C₄ to C₁₈branched alkane group, a C₁₀ to C₃₆ branched alkane group, or a C₁₀ toC₃₆ branched alkane group.

Aspect 62. The polymer defined in any one of aspects 56-60, wherein thecyclic alkane group is any carbon number cyclic alkane group disclosedherein, e.g., a C₄ to C₃₆ cyclic alkane group, a C₄ to C₁₈ cyclic alkanegroup, a C₆ to C₁₈ cyclic alkane group, or a C₆ to C₁₀ cyclic alkanegroup.

Aspect 63. The polymer defined in any one of aspects 56-60, wherein thearomatic group is a benzene group, a toluene group, an ethylbenzenegroup, a xylene group, or a mesitylene group.

Aspect 64. The polymer defined in any one of aspects 56-60, wherein thehalogenated hydrocarbon group is any carbon number halogenatedhydrocarbon group disclosed herein, e.g., a C₁ to C₃₆ halogenatedhydrocarbon group, a C₁ to C₁₈ halogenated hydrocarbon group, a C₁ toC₁₂ halogenated hydrocarbon group, or a C₁ to C₈ halogenated hydrocarbongroup.

Aspect 65. An article comprising the polymer defined in any one ofaspects 33-64.

We claim:
 1. A supported chromium catalyst comprising: a solid support;and from about 0.01 to about 20 wt. % chromium, based on the weight ofthe catalyst; wherein: the chromium has an average valence of less thanor equal to about 5.25; at least one bonding site on the chromium has aligand with one of the following formulas: —O-Hydrocarbon group or—O-Halogenated hydrocarbon group; and a molar ratio of the Hydrocarbongroup or Halogenated hydrocarbon group to chromium is in a range fromabout 0.5:1 to about 1.5:1.
 2. The catalyst of claim 1, wherein thecatalyst comprises less than or equal to about 75 wt. % of chromium(VI), based on the total amount of chromium.
 3. The catalyst of claim 1,wherein the chromium has average valence of less than or equal to about4.5.
 4. The catalyst of claim 1, wherein the solid support comprises asolid oxide, a chemically-treated solid oxide, a zeolite, or anycombination thereof.
 5. The catalyst of claim 1, wherein the catalystcomprises chromium/silica, chromium/silica-titania,chromium/silica-titania-magnesia, chromium/silica-alumina, orchromium/silica-coated alumina.
 6. The catalyst of claim 1, wherein thehydrocarbon group is an aromatic group.
 7. The catalyst of claim 1,wherein the hydrocarbon group is a linear alkane group, a branchedalkane group, or a cyclic alkane group.
 8. The catalyst of claim 1,wherein: the at least one bonding site on the chromium has a ligand withthe following formula: —O-Hydrocarbon group; and the —O-Hydrocarbongroup is an alkoxy group or an aryloxy group.
 9. The catalyst of claim1, wherein the catalyst comprises from about 0.2 to about 10 wt. %chromium.
 10. The catalyst of claim 9, wherein the catalyst comprisesless than or equal to about 40 wt. % of chromium (VI), based on thetotal amount of chromium.
 11. The catalyst of claim 9, wherein thechromium has average valence of less than or equal to about
 4. 12. Thecatalyst of claim 9, wherein the catalyst comprises chromium/silica,chromium/silica-titania-magnesia, chromium/silica-alumina, orchromium/silica-coated alumina.
 13. The catalyst of claim 12, whereinthe hydrocarbon group is an aromatic group.
 14. The catalyst of claim12, wherein the hydrocarbon group is a linear alkane group or a branchedalkane group.
 15. The catalyst of claim 12, wherein the hydrocarbongroup is a cyclic alkane group.
 16. The catalyst of claim 1, wherein thecatalyst comprises chromium/sulfated alumina, chromium/fluoridedalumina, chromium/fluorided silica-alumina, or chromium/fluoridedsilica-coated alumina.
 17. The catalyst of claim 1, wherein thehydrocarbon group is a methane group, an ethane group, a propane group,a n-butane group, an isobutane group, a n-pentane group, a neopentanegroup, an isopentane group, a n-hexane group, a n-heptane group, an-octane group, a n-decane group, or a n-dodecane group.
 18. Thecatalyst of claim 1, wherein the hydrocarbon group is a benzene group, atoluene group, an ethylbenzene group, a xylene group, or a mesitylenegroup.